Drive apparatus, drive method, and optical device

ABSTRACT

Noise produced during phase-difference changes is minimized without decreasing the responsiveness of a vibration-wave motor. A lens-side MCU for a lens barrel controls a drive apparatus that applies a drive voltage to the vibration-wave motor by outputting an A-phase drive signal and a B-phase drive signal thereto. The lens-side MCU uses, for example, a drive-voltage setting unit and a duty-cycle change unit to change the drive voltage. Also, the lens-side MCU is provided with a phase-difference change unit that changes the phase difference between the A-phase drive signal and the B-phase drive signal. When driving the vibration-wave motor, the lens-side MCU changes the drive voltage to V reg , and when the phase-difference change unit is changing the aforementioned phase difference, the drive voltage is changed to V 1 , V 1  being greater than zero and less than V reg .

This application is a Divisional of application Ser. No. 15/843,785filed Dec. 15, 2017 which is a Divisional of Ser. No. 15/152,001 filedMay 11, 2016 which is a Divisional of application Ser. No. 14/381,063filed Dec. 29, 2014, which is a National Stage of PCT/JP2013/055522,filed Feb. 28, 2013, and claims the benefit of priority (priorities)from Japanese Patent Application No. 2013-022196 filed Feb. 7, 2013,Japanese Patent Application No. 2012-287812 filed Dec. 28, 2012,Japanese Patent Application No. 2012-286941 filed Dec. 28, 2012,Japanese Patent Application No. 2012-059692 filed Mar. 16, 2012, andJapanese Patent Application No. 2012-042439 filed Feb. 28, 2012, theentire contents of the prior applications being incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a drive apparatus, a drive method andan optical device.

BACKGROUND ART

(1) A technique of suppressing the generation of abnormal noise relatedto the driving of a vibration wave motor has been known (for example,refer to Patent Document 1). In Patent Document 1, abnormal noise whenstopping the vibration-wave motor is suppressed by causing the phasedifference between an A-phase drive signal and a B-phase drive signal togradually vary from 90 deg to 0 deg.

(2) An imaging device that performs processing such as auto-focus bydriving an optical system by way of a vibration-wave motor has beenknown (Patent Document 2).

(3) A vibration actuator causes a progressive vibration wave(hereinafter abbreviated as progressive wave) to generate at the drivingface of an elastic body using the expansion and contraction of apiezoelectric body, causing an elliptic motion to occur at the drivingface by way of this progressive wave, thereby driving a moving elementin pressurized contact with the wave crest of the elliptic motion (forexample, refer to Patent Document 3). Such a vibration actuator has acharacteristic in having high torque even at low revolutions, and in thecase of equipping to a drive apparatus, it is possible to omit gears inthe drive apparatus. For this reason, it is possible to achieve quietingby elimination gear noise, and the positioning accuracy also improves.This vibration actuator has been equipped to some electric cameras. Inaddition, some electric cameras can perform photography of a movingimage in addition to photography of still images (refer to PatentDocument 4). In the case of performing photography of a moving image,normally the capturing of sound is also performed.

(4) Conventionally, two vibration signals having different phases fromeach other are applied to a piezoelectric effect element in order todrive the vibration actuator. The frequency of the vibration signalinputted starts from a frequency (startup frequency) between the drivefrequency used in order to drive the vibration actuator and a resonancefrequency of a next higher-order vibration mode to a vibration mode(drive mode) including this drive frequency, and gradually lowers to thedrive frequency (for example, refer to Patent Document 5).

(5) Conventionally, the drive apparatus of a vibration actuator hascontrolled the operation of the vibration actuator by causing the phasedifference and frequency of alternating signals input to the vibrationactuator to vary (for example, Patent Document 6).

[Patent Document 1]: Japanese Unexamined Patent Application, PublicationNo. 2002-199749

[Patent Document 2]: Japanese Unexamined Patent Application, PublicationNo. 2009-153286

[Patent Document 3]: Japanese Patent Publication No. H01-017354

[Patent Document 4]: Japanese Unexamined Patent Application, PublicationNo. H08-080073

[Patent Document 5]: Japanese Unexamined Patent Application, PublicationNo. H03-022873

[Patent Document 6]: Japanese Patent Publication No. 4765405

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

(1) Upon performing stopping of a vibration-wave motor and reverserotation to the driving direction, the phase difference between theA-phase drive signal and B-phase drive signal has been made to change.With a method of causing the phase difference to gradually change, theresponsiveness of the vibration-wave motor is harmed, as in PatentDocument 1.

(2) Upon switching the driving direction of an optical system by way ofa vibration-wave motor, there has been a problem in that abnormal noiseoccurs. Upon switching the driving direction with the invention ofPatent Document 2, driving of the optical system is temporarily stoppedby causing the voltage application to the vibration-wave motor to stop.At this time, abnormal noises generate accompanying the energy riseinside the drive circuit, upon performing voltage application to thevibration-wave motor for driving after switching direction. Theseabnormal noises are then recorded during moving image photography, etc.by the imaging device, for example.

(3) During moving image photography, when the lens is driven inauto-focus (hereinafter abbreviated as AF), the sound at the time ofoperation start of the vibration actuator is captured along with themoving image. The sound at the time of operation start of the vibrationactuator is generated from the stator (vibrator) upon causing the drivevoltage to change from 0 V step-wise to a predetermined voltage duringthe driving of the vibration actuator.

(4) The above-mentioned startup frequency cannot be defined as such ahigh frequency because it is limited to a frequency between the drivefrequency and the resonance frequency of the next higher-order vibrationmode of this drive mode. Therefore, due to not being started from asufficiently high frequency at the time of startup, an outbreak soundmay generate by the vibrator 20 suddenly beginning vibration.

In recent years, there are many cases of a vibration actuator being usedin cameras for moving image photography, and in these case, thisoutbreak sound is captured during moving image photography, etc. Inparticular, during moving image photography, the generation of thisabnormal noise is further actualized since a wobbling operation isperformed and the power source is frequently turned ON-OFF.

(5) The drive apparatus of Patent Document 6 enters a state in whichelectricity is always being supplied during control of the vibrationactuator; therefore, there has been a problem in that electricityconsumption rises.

The object of the present invention is to provide a drive apparatus, adrive method and an optical device that can suppress the generation ofabnormal noise. Another object of the present invention is to provide adrive apparatus and optical device that can reduce the electricityconsumption of a vibration actuator during control.

Means for Solving the Problems

A first aspect of the present invention provides an optical deviceincluding: a vibration actuator for which a driving direction changesaccording to a phase difference between a first drive signal and asecond drive signal; a drive apparatus that applies a drive voltage tothe vibration actuator by outputting the first drive signal and thesecond drive signal; a drive voltage change unit that changes the drivevoltage; and a phase difference change unit that changes the phasedifference, wherein the drive voltage change unit changes the drivevoltage to a first voltage in a case of driving the vibration actuator,and changes the drive voltage to a second voltage that is greater than 0and less than the first voltage in a case of the phase difference changeunit changing the phase difference.

A second aspect of the present invention provides a drive apparatus,including: a signal generation unit that generates a pair of drivesignals; an electro-mechanical conversion element to which the drivesignals generated by the signal generation unit are applied; a vibratingbody that generates a drive force by way of vibration of theelectro-mechanical conversion element; a moving body that is underpressurized contact with the vibrating body and is driven by way of thedrive force; and a control unit that sets a frequency and phasedifference of the drive signals, wherein the control unit changes thephase difference after setting the frequency to a holding frequency atwhich a drive speed of the moving body becomes substantially zero, whenchanging a driving direction of the moving body.

A third aspect of the present invention provides an optical device,including: vibration actuator that drive a lens using a drive forcegenerated at a driving face by way of excitation of anelectro-mechanical conversion element; a drive control unit thatprovides two drive signals to the vibration actuator; and a photographysetting unit that can select a moving image photography mode, whereinthe drive control unit can change a speed of the vibration actuator, ina case of the photography setting unit selecting the moving imagephotography mode, by changing a phase difference of the two drivesignals, and changing a frequency of the two drive signals to correspondto the phase difference thus changed, while maintaining a voltage of thetwo drive signals to be constant.

A forth aspect of the present invention provides a drive apparatus,including: a vibrating part having an electro-mechanical energyconversion element to which two drive signals having variable phasedifference are inputted; a relative motion part that relatively moves inrelation to the vibrating part, by way of a drive force generated at thevibrating part according to vibration of the electro-mechanical energyconversion element; and a control unit that inputs the two drive signalsto the electro-mechanical energy conversion element at a startupfrequency that is higher than a drive frequency used in driving, whilemaintaining at phase difference at which the relative motion part is ina stopped state, and when gradually reducing the frequency of the twodrive signals from the startup frequency and reaching the drivefrequency, sets the phase difference to a phase difference that enablesthe relative motion part to relatively move in relation to the vibratingpart.

A fifth aspect of the present invention provides a method of driving avibration actuator, wherein the vibration actuator includes: a vibratingpart having an electro-mechanical energy conversion element to which twodrive signals having variable phase difference are inputted; and arelative motion part that relatively moves in relation to the vibratingpart, by way of a drive force generated at the vibrating part accordingto vibration of the electro-mechanical energy conversion element, themethod comprising the steps of: during startup of the vibrationactuator, inputting the two drive signals to the electro-mechanicalenergy conversion element in a state maintaining a phase differencetherebetween at a phase difference at which the relative motion partstays in a stopped state, and at a startup frequency that is higher thanthe drive frequency used in driving of the vibration actuator; andsetting the phase difference to a phase difference at which the relativemotion part can relatively move in relation to the vibrating part, upongradually reducing the frequency of the two drive signals from thestartup frequency and reaching the drive frequency.

A sixth aspect of the present invention provides a drive apparatus forcontrolling driving of a vibration actuator that generates a driveforce, by applying two-phase alternating signals having different phasesto a piezeoelectric body provided to a vibrating body to cause thevibrating body to vibrate, the drive apparatus comprising: a speedcontrol unit that controls a drive speed of the vibration actuator, bycausing a frequency of the two-phase alternating signals applied to thepiezoelectric body to change; a frequency storage unit that stores apredetermined frequency; and a stop determination unit that determineswhether the vibration actuator is stopped, wherein the speed controlunit causes the frequency of the alternating signals applied to thepiezoelectric body to change to the predetermined frequency stored inthe frequency storage unit, in a case of the stop determination unithaving determined that the vibration actuator is stopped.

A seventh aspect of the present invention provides a drive apparatusthat controls driving of a vibration actuator that generates a driveforce, by applying two-phase alternating signals having different phasesto a piezeoelectric body provided to a vibrating body, the driveapparatus comprising: a speed control unit that controls a drive speedof the vibration actuator, by causing a frequency of the two-phasealternating signals applied to the piezoelectric body to change; and astop determination unit that determines whether the vibration actuatoris stopped, wherein the speed control unit causes the frequency of thealternating signals applied to the piezoelectric body to change so as toapproach an electrical resonance frequency, in a case of the stopdetermination unit having determined that the vibration actuator isstopped.

A eighth aspect of the present invention provides an optical device,including: an electro-mechanical energy conversion element to which adrive signal is applied from a drive circuit; a vibrating body thatgenerates a drive force by way of the electro-mechanical energyconversion element; a moving body that is driven by the drive force ofthe vibrating body; and a control unit that performs first control tocontrol so that the drive signal becomes a first frequency when causingthe moving body to drive, and performs second control to control so thatthe drive signal becomes a second frequency when the moving body isstopped, wherein the drive circuit has a smaller amount of powerconsumption when the drive signal is the second drive signal than whenthe drive signal is the first drive signal.

Effects of the Invention

According to the present invention, it is possible to suppress thegeneration of abnormal noise.

In addition, it is possible to reduce the electricity consumption of avibration actuator during control.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a lens barrel according to a firstembodiment of the present invention;

FIG. 2 is a schematic view of a vibration-wave motor provided to a lensbarrel according to the first embodiment of the present invention;

FIG. 3 is a control block diagram of a lens barrel according to thefirst embodiment of the present invention;

FIG. 4 is a schematic electrical circuit diagram showing an example of abooster unit;

FIG. 5 is a graph illustrating the relationship between the drivevoltage and duty cycle;

FIG. 6 is a graph showing the relationship between the frequency ofdrive signals applied to the vibration-wave motor and the rotationalspeed of the vibration-wave motor;

FIG. 7 is a graph showing the relationship between the phase differencebetween an A-phase drive signal and B-phase drive signal applied to thevibration-wave motor, and the rotational speed of the vibration-wavemotor;

FIG. 8 is a flowchart related to control of a drive apparatus by acontrol device of the lens barrel according to the first embodiment ofthe present invention;

FIG. 9 is a timing chart showing an example of control of the driveapparatus by the control device of the lens barrel according to thefirst embodiment of the present invention;

FIG. 10 is a table showing the relationship of a change rate of thephase difference between the A-phase drive signal and the B-phase drivesignal and the abnormal noise suppression level during phase differencechange;

FIG. 11 is a control block diagram of a lens barrel according to asecond embodiment of the present invention;

FIG. 12 is a flowchart related to control of the drive apparatus by thecontrol device of the lens barrel according to the second embodiment ofthe present invention;

FIG. 13 is a flowchart related to control of the drive apparatus by thecontrol device of the lens barrel according to the second embodiment ofthe present invention;

FIG. 14 is a schematic view of a lens barrel according to a thirdembodiment of the present invention;

FIG. 15 is a schematic view of a vibrating body of the vibration-wavemotor;

FIG. 16 is a graph showing phase difference—rotational speedcharacteristic of the vibration-wave motor;

FIG. 17 is a graph showing a frequency—rotational speed characteristicof the vibration-wave motor;

FIG. 18 is a block diagram showing the drive apparatus according to athird embodiment of the present invention;

FIG. 19 is a flowchart related to the drive control of thevibration-wave motor by the drive apparatus according to the thirdembodiment of the present invention;

FIGS. 20A to 20C provide a timing chart example related to drive controlof the vibration-wave motor by the drive apparatus according to thethird embodiment of the present invention;

FIG. 21 is a graph illustrating a holding frequency;

FIG. 22 is a flowchart related to setting processing of the holdingfrequency;

FIG. 23 is a diagram illustrating a electric camera of a fourthembodiment of the present invention;

FIG. 24 is a diagram illustrating a lens barrel of the fourth embodimentof the present invention;

FIG. 25 is a diagram illustrating a vibrator of a vibration-wave motoraccording to the fourth embodiment of the present invention;

FIG. 26 is a block diagram illustrating a drive apparatus of thevibration-wave motor;

FIG.27A is a graph showing the relationship of the rotational speed ofthe vibration-wave motor relative to the phase difference of the drivesignals, and FIG.27B is a graph showing the relationship of rotationalspeed of the vibration-wave motor relative to the drive frequency;

FIG. 28 is a timing chart illustrating the operations of a firstoperation example of the drive apparatus according to the fourthembodiment;

FIG. 29 is a flowchart illustrating the operations of the firstoperation example of the drive apparatus according to the fourthembodiment;

FIG. 30 is a timing chart illustrating the operations of a secondoperation example of the drive apparatus according to the fourthembodiment of the present invention;

FIG. 31 is a view illustrating a lens barrel according to a fifthembodiment of the present invention;

FIG. 32 is a view illustrating a vibration-wave motor according to thefifth embodiment;

FIG. 33 is a view illustrating the operating principle of thevibration-wave motor according to the fifth embodiment;

FIG. 34 is a view illustrating a camera including a lens barrel equippedwith a vibration actuator driven by a drive apparatus according to asixth embodiment;

FIG. 35 is a block diagram illustrating a vibration actuator and a driveapparatus of a vibration-wave actuator according to the sixthembodiment;

FIG. 36 is a view illustrating the lens barrel equipped with thevibration actuator driven by the drive apparatus according to the sixthembodiment;

FIG. 37 is a graph showing the relationship between the phase differencebetween the A-phase and B-phase and the rotational speed of a movingelement;

FIG. 38 is a graph showing the relationship between the frequency of thedrive signal and the impedance of the vibration actuator;

FIG. 39 is a graph showing an example of lens driving by the vibrationactuator according to the sixth embodiment;

FIG. 40 is a schematic view illustrating the overall configuration of acamera 701 according to a seventh embodiment;

FIG. 41 is a diagram illustrating the configuration of anultrasonic-wave motor 720 according to the seventh embodiment;

FIG. 42 is a diagram illustrating the configuration of a drive apparatus330 connected to the ultrasonic-wave motor 720 of the seventhembodiment;

FIGS. 43A and 43B provide graphs showing the characteristics of theultrasonic-wave motor 720 according to the seventh embodiment;

FIG. 44 is a timing chart illustrating the driving pattern of the driveapparatus 730 in wobbling operation according to the seventh embodiment;

FIG. 45 is a timing chart illustrating the driving pattern of a driveapparatus in the wobbling operation of a comparative example; and

FIG. 46 is a graph comparing between the electricity consumptions ofultrasonic-wave motors according to the comparative example and theseventh embodiment.

EXPLANATION OF REFERENCE NUMERALS

10,30: lens barrel, 12: vibration-wave motor, 14: drive apparatus,15,35: lens-side MCU, 17: storage unit, 20: camera body, 21: body-sideMCU, 141: drive pulse generation unit, 142: booster unit, 151: frequencychange unit, 152: drive voltage setting unit, 153: duty-cycle changeunit, 154,35-4: phase difference change unit, 35-3: power source voltagechange unit, 35-5: change rate setting unit, 50: level table, 201:vibration-wave motor, 202: lens barrel, 280: drive circuit, 281: controlunit, 282: oscillation part, 283: phase shifting unit, 284 a, 284 b;amplifier, 290: drive apparatus, 261: vibrating body, 262: moving body,f0: holding frequency, f9, f10: natural frequency, 301: camera, 310:vibration-wave motor, 313: piezoelectric body, 320: lens barrel, 339:contrast detection unit, 341: drive control unit, 347: photographysetting unit, 350: vibration-wave motor, 353: piezeoelectric body, L3:third lens unit, 501: lens barrel, 502: camera, 520: vibrator, 521:piezoelectric body, 522: elastic body, 522 a; driving face, 528: movingelement, 600: vibration actuator, 601: drive apparatus, f1: startupfrequency, f3: resonance frequency, fs: drive frequency, 710: lensbarrel, 720: ultrasonic-wave motor,722: vibrator, 724: piezoelectricelement, 730: drive apparatus, 731: control unit, 731 a; speed controlpart,731 b; stop determination part,732: drive circuit, 733: storageunit, 734: speed detection unit.

PREFERRED MODE FOR CARRYING OUT THE INVENTION First Embodiment

FIG. 1 is a schematic view showing the configuration of a lens barrelaccording to a first embodiment of the present invention. A lens barrel10 is a lens barrel for an imaging device such as a digital camera. Thelens barrel 10 includes an outer fixed cylinder 101, a first inner fixedcylinder 102 and second inner fixed cylinder 103. The outer fixedcylinder 101 covers an outer circumferential part of the lens barrel 10.The first inner fixed cylinder 102 and second inner fixed cylinder 103are present more on the inner circumferential side than the outer fixedcylinder 101, with the first inner fixed cylinder 102 being positionedon a subject side, and the second inner fixed cylinder 103 beingpositioned on the image side.

Between the outer fixed cylinder 101 and first inner fixed cylinder 102,a vibration-wave motor (vibration actuator) 12, drive apparatus 14, andgear unit module 104 are provided, and are fixed to the first innerfixed cylinder 102. The gear unit module 104 has a reduction gear 105that reduces and transmits the output of the vibration-wave motor 12.

In addition, from the subject side, a first lens unit L1 and second lensunit L2 are fixed to the first inner fixed cylinder 102. From thesubject side, a fourth lens unit L4 is fixed to the second inner fixedcylinder 103. Between the second lens unit L2 and fourth lens unit L4,the third lens unit L3 is arranged that is an AF lens for focusingretained in an AF ring 107. In other words, the first lens unit L1,second lens unit L2, third lens unit L3 and fourth lens unit L4 arearranged in order in an optical axis direction from the subject side toan imaging element side.

Between the AF ring 107 and first inner fixed cylinder 102, a cam ring106 is provided to rotate freely about the optical axis direction. Thecam ring 106 rotates by way of the output of the vibration-wave motor 12transmitted by way of the reduction gear 105. In addition, on the innerside of the cam ring 106, a key groove 106 a is cut in a spiral shape inthe circumferential direction. In addition, a fixed pin 107 a isprovided to the outer circumferential side of the AF ring 107. Thisfixed pin 107 a is inserted into the key groove 106 a of the cam ring106.

In addition, the drive apparatus 14 is arranged at a retention unit 101a that overhangs from an inner circumferential side of the outer fixedcylinder 101 to inside. The drive apparatus 14 is electrically connectedto the vibration-wave motor 12, and causes the vibration-wave motor 12to drive.

The output of the vibration-wave motor 12 causes the cam ring 106 torotate through the reduction gear 105, whereby the fixed pin 107 a movesbeing guided in the key groove 106 a, and causes the AF ring 107 to movein the optical axis direction. In addition, the output of thevibration-wave motor 12 can cause the AF ring 107 to stop by causing thecam ring 106 to stop. In other words, the drive apparatus 14 can causethe third lens unit L3 to move by driving the AF ring 107 in the opticalaxis direction by way of causing the vibration-wave motor 12 to drive,and thus can cause a subject focused on the imaging element to form animage.

FIG. 2 is a schematic view showing the configuration of the vibrationwave motor 12. The vibration-wave motor 12 is a rotating shaft-type(S-type) vibration-wave motor, and includes a vibrator 121, movingelement 124, fixed member 125, bearing 126, output shaft 127,pressurizing member 128, bearing receiver 129, stopper 130, rubbermember 131 and gear member 132.

The vibrator 121 has an elastic body 122 and piezoelectric body 123. Theelastic body 122 is formed from a metallic material having a largeresonance sharpness. The shape of the elastic body 122 forms an annularshape. The elastic body 122 consists of a comb-tooth part 122 a and abase part 122 b. The piezoelectric body 123 is joined at one face of thebase part 122 b, and the comb-tooth part 122 a is provided to theopposing face of this face. The comb-tooth part 122 a has a tip end faceof a projecting portion thereof that forms a driving face, andpressurized contacts the moving element 124. At the driving face of theelastic body 122, a resin film is formed for abrasion resistancesecurement when driven at high speed. The material of this resin film,for example, has polyamideimide as a main component, and PTFE is addedthereto. This resin film has a Young modulus on the order of 4 to 8 GPa,and the film thickness thereof is no more than 50 μm, for example.

The piezoelectric body 123 is an electro-mechanical conversion elementsuch as a piezoelectric element or electrorestrictive element thatconverts electrical energy to mechanical energy. The piezeoelectric body123 is divided into two phases (A-phase, B-phase) along thecircumferential direction, and is arranged so that poles arealternatingly arranged every ½ wavelength for each phase, and aninterval of ¼ wavelength is open between the A-phase and B-phase. Thephase difference between the drive signal output to the A-phase of thepiezoelectric body 123 and the drive signal output to the B-phasethereof is variable. When the respective drive signals are applied tothe A-phase and B-phase of the piezoelectric body 123, the piezoelectricbody 123 excites. Deflection of the base part 122 b of the elastic body122 due to excitation of the piezoelectric body 123 is magnified by thecomb-tooth part 122 a of the elastic body 122, and makes a progressivewave at the tip end of the driving face of the comb-tooth part 122.

The moving element 124 is formed from a light metal such as aluminum. Asliding face of the moving element 124 that pressurized contacts thecomb-tooth part 122 a is subjected to Alumite treatment for an abrasionresistance improvement.

The output shaft 127 is joined so as to rotate together with the movingelement 124 via the rubber member 131. The rubber member 131 has afunction of joining the moving element 124 and output shaft 127 with theadhesion by way of rubber, and a function of absorbing vibrations inorder not to transmit vibration from the moving element 124 to theoutput shaft 127.

The pressurizing member 128 is arranged between the gear member 132fixed to the output shaft 127 and the bearing receiver 129. The bearingreceiver 129 is inserted inside of the bearing 126. The bearing 126 isinserted inside of the fixed member 125. The gear member 132 is insertedso as to fit in the notched parts (D cut) (not illustrated) of theoutput shaft 127. Then, the gear member 132 is fixed by the stopper 130,and rotates along with the output shaft 127. It should be noted that apressure force adjusting washer (not illustrated) is arranged betweenthe pressure member 128 and the bearing receiver 129.

FIG. 3 is a control block diagram of the lens barrel according to thefirst embodiment of the present invention. FIG. 3 illustrates a camerabody 20 along with the lens barrel 10. In FIG. 3, the lens barrel 10includes the vibration-wave motor 12, drive apparatus 14, lens-side MCU(Micro Control Unit) 15, detection unit 16 and storage unit 17.

The drive apparatus 14 includes a drive pulse generation unit 141 andbooster unit 142, and drives the vibration-wave motor 12 by applyingdrive voltage to the vibration-wave motor 12. The lens-side MCU 15includes a frequency change unit 141, drive voltage setting unit 152,duty-cycle change unit 153 and phase difference change unit 154, andcontrols the drive apparatus 14.

The camera body 20 includes a body-side MCU 21.

The drive pulse generation unit 141 generates a drive pulse for theA-phase and a drive pulse for the B-phase, and outputs to the boosterunit 142. The drive pulse generation unit 141 can change the frequencyof the drive pulse for the A-phase and the drive pulse for the B-phase,duty cycle (value arrived at by dividing pulse width by pulse period),and phase difference, based on the control of the lens-side MCU 15.

The booster unit 142 has a circuit configuration like that shown in FIG.4, for example, and outputs the A-phase drive signal and B-phase drivesignal based on the drive pulse for the A-phase and drive pulse for theB-phase input from the drive pulse generation unit 141. The booster unit142 outputs the A-phase drive signal and B-phase drive signal to thevibration-wave motor 12.

The vibration wave motor 12 is driven according to the A-phase drivesignal and B-phase drive signal. The drive voltage driving thevibration-wave motor 12 becomes substantially the average amplitude ofthese drive signals, i.e. a value arrived at by dividing the timeintegral of the voltage of a predetermined period by the time. In thecase of the drive signal being a square wave that changes between zeroand a predetermined maximum voltage V_(MAX) as shown in FIG. 5, theproduct of the maximum voltage V_(MAX) of the drive signal and the dutycycle is an average amplitude V_(AVE), and this average amplitudeV_(AVE) corresponds to the drive voltage. In the example of FIG. 3, themaximum output voltage of the booster unit 142 corresponds to themaximum voltage V_(MAX) of FIG. 5, and the product with the duty cyclechanged by the duty cycle changed by way of the duty-cycle change unit153 becomes the drive voltage.

In order to change the drive voltage, it is sufficient to change theamplitude, duty cycle or both thereof. In the first embodiment, thedrive voltage is changed by changing the duty cycle by way of theduty-cycle change unit 153.

When the vibration-wave motor 12 is rotating, the drive voltage is setto V_(reg). Then, in the present invention, when changing the phasedifference in order to stop the vibration-wave motor 12 or performreversing the driving direction, the drive voltage is set to V₁, whichis smaller than V_(reg) and not zero. Since the amplitude of vibrationgenerated at the vibrator 121 is great in a state in which the drivevoltage is set to V_(reg), abnormal noise tends to generate in a case ofchanging the phase difference with the drive voltage remaining asV_(reg) as is conventionally. In the present invention, the generationof abnormal noise is reduced by setting the drive voltage to V₁ duringphase difference changing.

The frequency change unit 151 of the lens-side MCU 15 changes thesetting of the drive pulse generation unit 14 for the frequency of thedrive pulses of the A-phase and B-phase. The frequency of the drivesignal outputted to the vibration-wave motor 12 is changed accompanyingchange of the frequency of the drive pulses, whereby the rotationalspeed of the vibration-wave motor 12 changes. The frequency-rotationalspeed characteristic of the vibration-wave motor 12 is as shown in FIG.6.

When the frequency of the drive signal becomes the frequency f₀ shown inFIG. 6, the rotational speed of the vibration-wave motor 12 becomesN₀rpm (for example, 0 rpm), and stops. When the frequency of the drivesignal becomes a frequency f₁, which is smaller than the frequency f₀,the vibration-wave motor 12 is driven at the rotational speed N₁rpm.Similarly, when the frequency of the drive signal becomes a frequencyf₂, which is smaller than the frequency f₁, the vibration-wave motor 12is driven at a rotational speed N₀rpm, which is faster than therotational speed N₁.

The drive voltage setting unit 152 sets the drive voltage applied to thevibration-wave motor 12. The duty-cycle change unit 153 changes thesetting of the drive pulse generation unit 141 for the duty cycle of theA-phase drive pulse and the B-phase drive pulse so that the drivevoltage set by the drive voltage setting unit 152 is applied.

The phase difference change unit 154 changes the setting of the drivepulse generation unit 141 for the phase difference between the drivepulse for the A-phase and the drive pulse for the B-phase outputted bythe drive pulse generation unit 141. The phase difference—rotationalspeed characteristic of the vibration-wave motor 12 is as shown in FIG.7.

As shown in FIG. 7, the rotational speed of the vibration-wave motor 12reaches a maximum speed of positive rotation (for example, clockwiserotation) when the phase difference is +90 deg, and reaches a maximumspeed of reverse rotation (for example, counter-clockwise rotation) whenthe phase difference is −90 deg. The setting of the drive pulsegeneration unit 141 for the phase difference between the drive pulse forthe A-phase and the drive pulse for the B-pulse is set to +90 deg or −90deg.

The lens-side MCU 15 performs communication with the body-side MCU 21.The lens-side MCU 15 sends lens information, for example, to thebody-side MCU 21. On the other hand, the body-side MCU 21 sends driveinstructions of the third lens unit L3 according to the vibration-wavemotor 12 to the lens-side MCU 15. A target position to which to drivethe third lens unit L3 is at least included in the drive instructions ofthe third lens unit L3.

The detection unit 16 is configured from an optical-type encoder,magnetic encoder, etc., detects the position and/or speed of the thirdlens unit L3 driven by the driving of the vibration-wave motor 12, andoutputs these detection values to the lens-side MCU 15 as electricalsignals (detection signals).

The storage unit 17 is ROM or the like, and a control program executedby the lens-side MCU 15 to control the lens barrel 10, lens informationand the like are stored therein.

FIG. 8 is a flowchart relating to control of the drive apparatus 14executed by the lens-side MCU 15. The processing in FIG. 8 is startedwhen the lens-side MCU 15 received a drive instruction for the thirdlens unit L3 from the body-side MCU 21.

In Step S300 in FIG. 8, the lens-side MCU 15 determines the rotationaldirection and rotational speed of the vibration-wave motor 12 based onthe drive instruction for the third lens unit L received from thebody-side MCU 21 and the detection signals detected by the detectionunit 16.

In Step S301, the lens-side MCU 15 judges whether to change the phasedifference between the drive pulse for the A-phase and the drive pulsefor the B-phase. The lens-side MCU 15 positively judges Step S301 in thecase of it being necessary to make the rotational direction reverse,based on the rotational direction of the vibration-wave motor 12 at themoment when starting Step S301 and the rotational direction of thevibration-wave motor 12 determined in Step S300. The lens-side MCU 15advances the processing to Step S302 in the case of Step S301 beingpositively judged, and advances the processing to Step S305 in the caseof Step S301 being negatively judged.

In Step S302, the lens-side MCU 15 changes the drive voltage to V₁. Forexample, the following such processing is performed using the drivevoltage setting unit 152 and the duty-cycle change unit 153. First, thedrive voltage setting unit 152 sets the drive voltage to V₁. Next, theduty-cycle change unit 153 changes the setting of the drive pulsegeneration unit 141 relating to the duty cycles of the drive pulses ofthe A-phase and B-phase, so that the average amplitudes of the A-phasedrive signal and B-phase drive signal become V₁.

In Step S303, the lens-side MCU 15 changes the phase difference betweenthe drive pulse of the A-phase and the drive pulse of the B-phase, basedon the rotational direction of the vibration-wave motor 12 determined inStep S300. For example, the phase difference change unit 154 of thelens-side MCU 15 changes the setting of the drive pulse generation unit141 relating to the phase difference to a phase difference correspondingto the rotational direction of the vibration-wave motor 12 determined inStep S300.

In Step S304, the lens-side MCU 15 changes the drive voltage to V_(reg).For example, the following such processing is performed using the drivevoltage setting unit 152 and the duty-cycle change unit 153. First, thedrive voltage setting unit 152 sets the drive voltage to V_(reg). Next,the duty-cycle change unit 153 changes the setting of the drive pulsegeneration unit 141 relating to the duty cycles of the drive pulses ofthe A-phase and B-phase, so that the average amplitudes of the A-phasedrive signal and B-phase drive signal become V_(reg).

In Step S305, the lens-side MCU 15 changes the frequencies of the drivepulses of the A-phase and B-phase to drive the vibration-wave motor 12.For example, the frequency change unit 151 of the lens-side MCU 15changes the setting of the drive pulse generation unit 141 relating tothe frequency of the drive pulses of the A-phase and B-phase from f₀ tof₁ or f₂.

In Step S306, the lens-side MCU 15 judges whether the third lens unit L3was driven until a target position of the third lens unit L3 included inthe drive instruction. For example, the lens-side MCU 15 detects theposition of the third lens unit L3 based on the detection signals of thedetection unit 16, and compares this position with the target positionof the third lens unit L3 included in the drive instruction. Thelens-side MCU 15 returns the processing to Step S305 in the case of StepS306 being negatively judged, and advances the processing to Step S307in the case of Step S306 being positively judged.

In Step S307, the lens-side MCU 15 changes the frequency of the drivepulses of the A-phase and B-phase to cause the vibration-wave motor 12to stop. For example, the frequency change unit 151 of the lens-side MCU15 changes the frequencies of the drive pulses of the A-phase andB-phase to f₀.

FIG. 9 is a timing chart relating to drive control of the vibration-wavemotor 12. FIG. 9 illustrates side-by-side the position of the third lensunit L3, rotational speed of the vibration-wave motor 12, setting valueof frequency in the drive pulse generation unit 141, setting value ofphase difference in the drive pulse generation unit 141 and timing chartof drive voltage, respectively.

In FIG. 9, the lens-side MCU 15 receives from the body-side MCU 21 thedrive instructions for the third lens unit L3 three times (for example,timing t1, t5, t11). The first time drive instruction is a driveinstruction to cause the third lens unit L3 to drive until a positionWbe on the optical axis. The second time drive instruction is a driveinstruction to cause the third lens unit L3 to drive until a positionWaf on the optical axis. The third time drive instruction is a driveinstruction to cause the third lens unit L3 to drive until a position W₀on the optical axis.

The lens-side MCU 15 changes the setting value of the frequency at thetiming t2 (Step S305) when receiving the first time drive instruction attiming t1, since it is no longer necessary to change the phasedifference (NO in Step S301 of FIG. 8). The rotational speed of thevibration-wave motor 12 gradually becomes faster in proportion as thesetting value of the frequency becomes smaller than f₀. The position ofthe third lens unit L3 reaches the target position Wbe at the timing t4(YES in Step S306), and subsequently the setting value of the frequencybecomes f₀ and the vibration-wave motor 12 stops (Step S307).

The lens-side MCU 15 first changes the drive voltage from V_(reg) to V₁(Step S302) when receiving the second time drive instruction at thetiming t5 since it is necessary to change the phase difference (YES inStep S301 of FIG. 8). Next, the lens-side MCU 15 changes the phasedifference between the drive pulse of the A-phase and the drive pulse ofthe B-phase at the timing t6 from +90 deg to −90 deg (Step S303). Whilechanging the phase difference, the drive voltage is maintained as is atV₁. The lens-side MCU 15 changes the drive voltage from V₁ to V_(reg)(Step S304) at the timing t7 after changing of the phase differencefinished. Subsequently, the lens-side MCU 15 changes the setting valueof the frequency at the timing t8 (Step S305). At this time, since thedistance that is necessary to drive the third lens unit L is longer thanwhen at the timing t2, the setting value of the frequency is set to belower than at the timing t2. The position of the third lens unit L3arrives at the target position Waf at the timing t10 (YES in Step S306),and subsequently the setting value of the frequency becomes f₀ and thevibration-wave motor 12 stops (Step S307).

The lens-side MCU 15 first changes the drive voltage from V_(reg) to V₁(Step S302) when receiving the third time drive instruction at thetiming t11 since it is necessary to change the phase difference (YES inStep S301 of FIG. 8). Next, the lens-side MCU 15 changes the phasedifference between the drive pulse of the A-phase and the drive pulse ofthe B-phase at the timing t12 from −90 deg to +90 deg (Step S303). Whilechanging the phase difference, the drive voltage is maintained as is atV₁. The lens-side MCU 15 changes the drive voltage from V₁ to V_(reg)(Step S304) at the timing t13 after changing of the phase differencefinished. Subsequently, the lens-side MCU 15 changes the setting valueof the frequency at the timing t14 (Step S305). The position of thethird lens unit L3 arrives at the target position W₀ at the timing t16(YES in Step S306), and subsequently the setting value of the frequencybecomes f₀, and the vibration-wave motor 12 stops (Step S307).

Abnormal noise upon changing the phase difference such as at the timingt6 and t12 can be suppressed enough to set the value of V₁ lowerrelative to the value of V_(reg). The effect of abnormal noisesuppression is not limited to only the phase difference change explainedin FIG. 9 and, for example, is effective also for a phase differencechange from 0 deg to +90 deg, a phase difference change from +90 deg to0 deg, a phase difference change from 0 deg to −90 deg, a phasedifference change from −90 deg to 0 deg, etc. In addition, lowering thedrive voltage to V₁ contributes also to a reduction in the electricityconsumption of the vibration-wave motor 12.

The below operating effects are obtained according to the firstembodiment explained above. The lens-side MCU 15 of the lens barrel 10controls the drive apparatus 14 that outputs the A-phase drive signaland B-phase drive signal to the vibration-wave motor 12, and appliesdrive voltage to the vibration-wave motor 12. The lens-side MCU 15includes the drive voltage setting unit 152 and duty-cycle change unit153, and changes the drive voltage applied to the vibration-wave motor12. In addition, the lens-side MCU 15 includes the phase differencechange unit 154, and changes the phase difference between the A-phasedrive signal and B-phase drive signal by changing the phase differencebetween the drive pulses of the A-phase and B-phase. The drive voltagesetting unit 152 and duty-cycle change unit 153 change the drive voltageto V_(reg) in the case of rotationally driving the vibration-wave motor12 (Step S304 in FIG. 8), and change the drive voltage to V₁ which isgreater than zero and smaller than V_(reg) in the case of the phasedifference change unit 154 changing the phase difference (Step S302 inFIG. 8). By configuring in this way, the lens barrel 10 can reduce theabnormal noise during phase difference changing without harming theresponsiveness of the vibration-wave motor 12.

Second Embodiment

A second embodiment of the present invention will be explained. In thesecond embodiment, a reduction in abnormal noise during phase differencechange is achieved by not only lowering the drive voltage prior tochanging the phase difference, but also setting the change rate of thephase difference to be low (slowing).

For the duty cycle of the drive pulse of each phase, the range of valueoptions thereof is limited by the resolving power of PWM, etc. Forexample, the duty cycle of the drive pulse is assigned to the settingvalues of 0 to 255, and it is not possible to set the setting value ofthe duty cycle to a value between “0” and “1”. The lower limit for thesetting value of V₁ is decided, for example, by the product of the dutycycle d1 corresponding to the setting value “1” and the maximum voltageVMAX of the drive signal.

The value of VMAX varies according to the circuit configuration, ambienttemperature, etc. of the drive apparatus of the vibration-wave motor 12.For example, the value of VMAX becomes larger as the ambient temperaturebecomes lower. In the case of the drive voltage serving as the level atwhich abnormal noise can be ignored being defined as Vs, there is a riskof the duty cycle ds such that V₁≤V_(S) when the value of V_(MAX) islarge becoming a value smaller than the duty cycle d1 corresponding tothe setting value “1”.

In the second embodiment, by setting the change rate of the phasedifference to be low in order to solve the problem in theabove-mentioned such design, the generation of abnormal noise issuitably suppressed even in the case of the lower limit for the settingvalue of V₁ being large. FIG. 10 is a table illustrating the abnormalnoise suppression effect by setting the change rate of the phasedifference to be low.

FIG. 10 is an example of a level table relating to the suppression levelof abnormal noise. In level table 50 exemplified in FIG. 10, in thecases of the proportion of V₁ relative to V_(reg) being 100%, 75%, 50%and 25%, the suppression levels of abnormal noise are shown for when thechange rate of the phase difference is 90 deg/msec, 30 deg/msec and 5deg/msec, respectively. The suppression level of abnormal noise is avalue determined in advance at the design stage of the lens barrel, andis divided into the three stages of level 1, level 2 and level 3. Whenthe suppression level is level 1, abnormal noise does not generate uponphase difference change. When the suppression level is level 2, abnormalnoise upon phase difference change does not stand out and can beignored. When the suppression level is level 3, the abnormal noiseduring phase difference change stands out. Abnormal noise standing outrepresents a state in which abnormal noise is recorded without confusingfor other noise, within recorded sound during moving image capture.

As is evident from looking at FIG. 10, for the suppression level ofabnormal sound, the level becomes lower as the proportion of V₁ relativeto V_(reg) is decided smaller. In other words, abnormal noise can besuppressed more as the proportion of V₁ relative to V_(reg) is decidedsmaller. In addition, for the suppression level of abnormal noise, thelevel comes to be lower as the change rate of the phase differencebecomes slower.

For example, when deciding the setting value of V₁ so that theproportion of V₁ relative to V_(reg) becomes 50% in the case of thechange rate of the phase difference being 90 deg/msec, the suppressionlevel of abnormal noise is level 2. On the other hand, in the case ofslowing the change rate of the phase difference to 30 deg/msec, thesetting value of V₁ can be decided so that the suppression level ofabnormal noise becomes level 2, even if the proportion of V₁ relative toV_(reg) is 75%. The lens barrel according to the second embodiment ofthe present invention, in the case of the suppression level being thesame, when the proportion of V₁ relative to V_(reg) is large, the changerate of the phase difference is set to be lower than when the proportionof V₁ relative to V_(reg) is small.

The lens barrel according to the second embodiment of the presentinvention includes the same configuration as FIG. 1. FIG. 11 is acontrol block diagram for the lens barrel according to the secondembodiment of the present invention. For the same configurations as thecontrol block diagram shown in FIG. 3 in the control block diagram shownin FIG. 11, the same reference numbers as FIG. 3 are assigned andexplanations thereof are omitted. It should be noted that, in thefollowing explanation, the setting value relating to the duty cycle ofthe drive pulse generation unit 141 is explained as being constant at apredetermined value. The drive voltage applied to the vibration-wavemotor 12 is changed based on the power source voltage of the boosterunit 142 (FIG. 4).

The lens barrel 30 in FIG. 11 includes a lens-side MCU 35 in place ofthe lens-side MCU 15. In addition, the lens barrel 30 further includes atemperature detection unit 38 that detects the ambient temperature. Thelens-side MCU 35 includes a power source voltage change unit 35-3 andphase difference change unit 35-4 in place of the duty-cycle change unit153 and phase difference change unit 154. Furthermore, the lens-side MCU35 newly includes a change rate setting unit 35-5.

The power source voltage change unit 35-3 changes the power sourcevoltage of the booster unit 142. When the power source voltage of thebooster unit 142 is changed, the amplitudes of the A-phase drive signaland B-phase drive signal change, and thus the drive voltage applied tothe vibration-wave motor 12 changes.

The change rate setting unit 35-5 sets the change rate of the phasedifference based on the proportion of V₁ relative to V_(reg) decided atthe design stage, and the setting value of the suppression level set inadvance. For example, in the case of V₁ being set to 75% of V_(reg), andthe suppression level being set to level 2 in advance, the change ratesetting unit 35-5 references the column of the level table 50 in whichthe proportion of V₁ relative to V_(reg) is 75%, and sets the changerate of the phase difference to a change rate such that the suppressionlevel is level 2, e.g., 30 deg/msec. It should be noted that the leveltable 50 is stored in the storage unit 17 or the like. For the settingvalue of the suppression level, it may be configured for the user to setusing an operation member that is not illustrated, or it may beconfigured so that the lens-side MCU 35 or body-side MCU 21automatically sets based on the operation mode of the imaging deviceequipped with the lens barrel 30. For example, it may be configured sothat, in the case of performing photography not accompanied by recordingof sound like in still image photography, the lens-side MCU 35 or thebody-side MCU 21 sets the suppression level to level 3, and in the caseof performing photography accompanied by the recording of sound like inmoving image photography, the lens-side MCU 35 or the body-side MCU 21sets the suppression level to level 1.

The phase difference change unit 35-4 changes the setting of the drivepulse generation unit 141 relating to the phase difference between thedrive pulse for the A-phase and the drive pulse for the B-phaseoutputted by the drive pulse generation unit 141. Upon doing so, thephase difference is changed based on the change rate set by the changerate setting unit 35-5.

FIG. 12 and FIG. 13 are flowcharts relating to the control of the driveapparatus 14 performed by the lens-side MCU 35. The processing of FIG.12 is initiated when the lens-side MCU 35 receives the drive instructionfor the third lens unit L3 from the body-side MCU 21. For processingthat is the same as that shown in FIG. 8 among the processing shown inFIG. 12 and FIG. 13, explanations thereof will be omitted.

In Step S401, the lens-side MCU 35 changes the drive voltage to V₁. Forexample, the drive voltage setting unit 152 of the lens-side MCU 35 setsthe drive voltage to V₁. Next, the power source voltage change unit 35-3changes the power source voltage of the booster unit 142 so that thedrive voltage becomes V₁.

In Step S402, the lens-side MCU 35 sets the change rate of the phasedifference. For example, the change rate setting unit 35-5 sets thechange rate of the phase difference based on the proportion of V₁relative to V_(reg), and the suppression level set in advance. It shouldbe noted that it may be configured so that the change rate setting unit35-5 references the level table 50 based on the proportion of V₁relative to V_(reg) to set the change rate of the phase difference.

In Step S403, the lens-side MCU 35 changes the phase difference betweenthe drive pulse of the A-phase and the drive pulse of the B-phase, basedon the change rate set in Step S402 and the rotational direction of thevibration-wave motor 12 determined in Step S300.

In Step S404, the lens-side MCU 35 judges whether the phase differenceof the drive pulse of the A-phase and the drive pulse of the B-phasechanged to a target value. Herein, target value indicates the phasedifference representing the rotational direction of the vibration-wavemotor 12 determined in Step S300 of FIG. 12. The lens-side MCU 35returns the processing to Step S403 in the case of Step S403 beingnegatively judged, and advances the processing to Step S304 of FIG. 12in the case of Step S404 being positively judged. The lens-side MCU 35changes the drive voltage to V_(reg) in Step S304 of FIG. 12, and thenadvances the processing to Step S305 of FIG. 13. Since the processing inFIG. 13 is the same processing for Steps S305, S306 and S307 in FIG. 8,explanations thereof will be omitted.

The following functional effects are obtained according to the secondembodiment explained above.

The lens-side MCU 35 of the lens barrel 30 controls the drive apparatus14 that outputs the A-phase drive signal and B-phase drive signal to thevibration-wave motor 12, and applies drive voltage to the vibration-wavemotor 12. The lens-side MCU 35 includes the drive voltage setting unit152 and power source voltage change unit 35-3, and changes the drivevoltage applied to the vibration-wave motor 12. The lens-side MCU 35includes the phase difference change unit 35-4, and changes the phasedifference between the A-phase drive signal and B-phase drive signal bychanging the phase difference between the drive pulses of the A-phaseand B-phase. The drive voltage setting unit 152 and the power sourcevoltage change unit 35-3 change the drive voltage to V_(reg) (Step S304in FIG. 12) in the case of causing the vibration-wave motor 12 torotationally drive, and change the drive voltage to V₁, which is largerthan zero and smaller than V_(reg) (Step S401 in FIG. 12) in the case ofthe phase difference change unit 154 changing the phase difference.

By configuring in this way, the lens barrel 30 can reduce abnormal noiseduring phase difference changing, without harming the responsiveness ofthe vibration-wave motor. In addition, the lens-side MCU 35 can reducethe abnormal noise during phase difference changing, even in a case ofnot being able to set V₁ to a sufficiently small value according to thecircuit configuration or ambient temperature of the drive apparatus ofthe vibration-wave motor 12, by the speed change setting unit 35-5setting the change rate of the phase difference suitably.

The embodiments explained above can be modified and implemented in thefollowing ways.

MODIFIED EXAMPLE 1

In the first embodiment, the lens-side MCU 15 is configured so that theduty-cycle change unit 153 changes the setting value of the duty cyclein the drive pulse generation unit 141. However, it may be configured sothat the lens-side MCU 15 includes the power source voltage change unit35-3 in place of the duty-cycle change unit 153. In addition, in thesecond embodiment, the lens-side MCU 35 is configured so that the powersource voltage change unit 35-3 changes the power source voltage of thebooster unit 142. However, it may be configured so that the lens-sideMCU 35 includes the duty-cycle change unit 153 in place of the powersource voltage change unit 35-3.

MODIFIED EXAMPLE 2

The vibration-wave motor driven by the drive apparatus 14 controlled bythe lens-side MCU 15 and 35 is not limited to only a rotating shaft-typemotor like that shown in FIG. 2. For example, it may be a ring-typevibration-wave motor. Control by way of the lens-side MCU 15 and 35 canbe performs similarly to the above-mentioned embodiments even if thevibration-wave motor is of ring type.

MODIFIED EXAMPLE 3

The present invention can be applied to electronic devices other thandigital cameras so long as being electronic devices that control a driveapparatus by a control device such as an MCU, and drive a vibration-wavemotor with this drive apparatus.

Third Embodiment

FIG. 14 is a schematic view of a lens barrel according to a thirdembodiment of the present invention. The lens barrel 202 in FIG. 14 is alens barrel for an imaging device such as a digital camera. Thevibration-wave motor 201 includes a vibrating body 261, a moving body262, a dampening support member 263 from a non-woven fabric or the like,and a pressurized contact means 264. The vibration-wave motor 201provides drive power for causing a lens unit L to drive in the opticalaxis direction relative to the lens barrel 202.

The vibrating body 261 has an elastic body 261 a and a piezoelectricbody 261 b. The elastic body 261 a is formed from a metallic materialhaving a large resonance sharpness. The shape of the elastic body 261 aforms an annular shape as shown in FIG. 15. The piezoelectric body 261 bis joined to one face of the round shape of the elastic body 261 a, anda comb-teeth part 221 in which grooves are cut is provided on theopposing face thereof.

The piezoelectric body 261 b is an electro-mechanical conversion elementthat converts electrical energy to mechanical energy. The piezeoelectricbody 123 is divided into two phases (A-phase, B-phase) along thecircumferential direction. Poles are arranged alternatingly arrangedevery ½ wavelength for each phase of the piezoelectric body 261 b. It isarranged so that an interval of ¼ wavelength is open between the A-phaseand B-phase of the piezoelectric body 262 b. A drive signal is outputtedfrom a drive circuit 280 to each phase of the piezoelectric body 261 b.The phase difference between the drive signal output to the A-phase andthe drive signals output to the B-phase of the piezoelectric body 261 bis variable. When the respective high-frequency voltages are applied tothe A-phase and B-phase of the piezoelectric body 261 b, thepiezoelectric body 261 b excites. Deflection of the base part 222 of theelastic body 261 a due to excitation of the piezoelectric body 261 b ismagnified by the comb-tooth part 221 of the elastic body 161 a, andmakes a progressive wave at the driving face 223 at the tip ends of thecomb-tooth part 221. It should be noted that, in the present embodiment,the piezoelectric body 261 b is made to be an electrode pattern forwhich a 9-peak progressive wave (9th order bending vibration wave) tendsto generate.

The moving body 262 is formed from a light metal such as aluminum. Themoving body 262 pressure contacts the driving face 223 by way of thepressure from the pressurized contact means 264 having the pressureplate and pressurizing member. Elliptic motion occurs at the crests ofthe wave of the progressive wave generated by the driving face 223. Themoving body 262 under pressurized contact with the driving face 223 isdriven by the friction from this elliptic motion to rotationally move.The rotational direction of the moving body 262 changes according to thephase difference between the drive signals of the A-phase and B-phase ofthe piezoelectric body 261 b.

A vibration absorbing member 266 such as of rubber that absorbsvibration in the optical axis direction of the moving body 262 isarranged in the moving body 262. The vibration absorbing member 266pressure contacts an output transfer unit 255 by way of the pressurizedcontact means 264. The rotational motion of the moving body 262 istransferred to the output transfer unit 255. However, for the outputtransfer unit 255, the movement in the optical axis direction andmovement in the radial direction are restricted by a bearing 256attached in a fixed member 251.

The output transfer unit 255 has a projecting part 255 a. Thisprojecting part 255 a fits together with a fork 254. The rotationalmotion of the output transfer unit 255 is transferred to the fork 254via the projecting part 255 a. Furthermore, the rotational motionthereof transfers to a cam ring 253. On the inner side of the cam ring253, a key groove 253 a is cut in a spiral shape in the circumferentialdirection. A fixed pin 252 a is provided to the outer circumferentialside of an AF ring 252. When the cam ring 253 rotates, the fixed pin 252a moves being guided in the key groove 253 a, and the AF ring 252retaining the lens unit L moves in the optical axis direction.

In the above-mentioned way, the progressive wave generated by thevibration-wave motor 201 is transferred to the AF ring 252 via themoving body 262, output transfer unit 255, fork 254 and cam ring 253,whereby the lens unit L is driven in the optical axis direction alongwith the AF ring 252. The lens barrel executes a wobbling operation,etc. using this driving.

FIG. 16 is a graph showing the relationship between the phase differencebetween the drive signals of the A-phase and B-phase and the rotationalspeed of the moving body 262. The rotational speed of the moving body262 reaches a maximum speed of positive rotation (for example, clockwiserotation) when the phase difference is +90°, and reaches a maximum speedof reverse rotation (for example, counter-clockwise rotation) when thephase difference is −90°.

FIG. 17 is a graph showing the relationship between the frequency ofdrive signals and the rotational speed of the moving body 262. Therotational speed of the moving body 262 is substantially zero when thefrequency of the drive signal is with a predetermined range. Herein,substantially zero refers to a state in which torque for only causingthe moving body 262 under pressurized contact with the vibrationabsorbing member 266, etc. to rotate is not generated. For example,within the range shown in FIG. 17, the rotational speed of the movingbody 262 becomes zero within the range from 28.5 kHz to 30.0 kHz. Inaddition, even if a lower frequency than 28.5 kHz or a higher frequencythan 30.0 kHz, a frequency exists at which a torque for only causing themoving body 262 under pressurized contact with the vibration absorbingmember 266, etc. to rotate is not generated, the cam ring 253, etc. arenot rotated, and the rotational speed of the moving body 262 issubstantially zero. The matter of such a frequency at which therotational speed of the moving body 262 becomes substantially zero isreferred to as holding frequency f0.

In the present invention, upon switching the rotational drivingdirection of the moving body 262, the frequency of the drive signal ischanged to the holding frequency f0 without stopping the voltageapplication to the vibration-wave motor 201. It is thereby possible toreduce the abnormal noise generating upon applying voltage again afterstopping voltage application.

FIG. 18 is a block diagram relating to the drive apparatus according tothe third embodiment of the present invention. A drive apparatus 290exemplified in FIG. 18 includes a vibration-wave motor 201 and drivecircuit 280. The drive circuit includes a control unit 281, oscillationpart 282, phase shifting unit 283, amplifiers 284 a and 284 b, detectionunit 285 and temperature measurement unit 286.

The oscillation part 282 oscillates a signal of a frequency set by thecontrol unit 281. The phase shifting unit 283 generates the signal ofthe A-phase and the signal of the B-phase based on an oscillation signaloscillated by the oscillation part 282. A phase difference between thissignal of the A-phase and signal of the B-phase is set by the controlunit 281.

The amplifier 284 a amplifies (boosts) the voltage amplitude of thesignal of the A-phase generated by the phase shifting unit 283 to avoltage set by the control unit 281. The drive signal of the A-phase isthereby generated. In addition, the amplifier 284 b amplifies (boosts)the voltage amplitude of the signal of the B-phase generated by thephase shifting unit 283 to a voltage set by the control unit 281. Thedrive signal of the B-phase is thereby generated.

The vibrating body 261 is driven based on the drive signal of theA-phase amplified by the amplifier 284 a, and the drive signal of theB-phase amplified by the amplifier 284 b. The detection unit 285 isconfigured by an optical encoder, magnetic encoder or the like, detectsthe position and/or speed of the lens unit L driven by the driving ofthe moving body 262, and outputs these detection values to the controlunit 281 as electrical signals (detection signals). The control unit 281acquires information relating to the position and/or speed of the lensunit L based on the detection signals from the detection unit 285.

The temperature measurement unit 286 measures the temperature of thevibration-wave motor 201. The temperature of the vibration-wave motor201 rises from the heat producing from friction between the vibratingbody 261 and the moving body 262. A temperature rise in thevibration-wave motor 201 adversely affects the driving ability thereof.The temperature measurement unit 286 outputs the measured temperaturesignal to the control unit 281. The control unit 281 estimates theinfluence on the driving ability imparted by the temperature of thevibration-wave motor 201, based on the temperature signal thereof.

The control unit 281 acquires a drive instruction relating to themovement direction and movement amount of the lens unit L from a CPU 203of the lens barrel 202. The control unit 281 controls the frequency setin relation to the oscillation part 282, the phase difference set inrelation to the phase shifting unit 283, and the voltage amplitude setin relation to the amplifiers 284 and 284 b, so that the lens unit L ispositioned at the target position decided based on the driveinstruction. It should be noted that the drive instruction acquired bythe control unit 281 is not limited to only instructions related tocombinations of movement direction and movement amount. For example, itmay include the patterns of movement speed and movement sequence (forexample, number of revolutions of wobbling operations). In addition, thedrive instruction acquired by the control unit 281 may be a combinationof movement direction and movement speed.

Drive control of the vibration-wave motor 201 of the present inventionwill be explained using FIG. 19 and FIGS. 20A to C. FIG. 19 is anexample of a flowchart relating to drive control of the vibration-wavemotor 201. FIGS. 20A to C are examples of timing charts relating todrive control of the vibration-wave motor 201. FIG. 20A is a timingchart relating to the phase difference between the drive signals of theA-phase and B-phase. FIG. 20B is a timing chart relating to theoscillation frequency of the oscillation part 282, i.e. frequency of thedrive signal. FIG. 20C is a timing chart relating to the revolutionspeed of the vibration-wave motor 201.

The processing of FIG. 19 starts execution when the control unit 281acquires a drive instruction. In Step S100, the control unit 281controls so as to set the holding frequency f0 in the oscillation part282, and the signal of the holding frequency f0 from the oscillationunit 282 is oscillated.

In Step S110, the control unit 281 sets the phase difference of +90° or−90° in the phase shifting unit 283, and changes the phase differencebetween the signal of the A-phase and the signal of the B-phaseoutputted by the phase shifting unit 283 (timing T0 to T1, and timing T3to T4 in FIG. 20). When the frequency oscillated by the oscillation unit282 is the holding frequency f0, the revolution speed of thevibration-wave motor 201 is substantially zero. Therefore, driving ofthe vibration-wave motor 201 will not become unstable, even if thecontrol unit 281 changes the phase difference in Step S110.

After changing of the phase difference in Step S110 ends, the controlunit 281 controls the frequency set in the oscillation part 282 based onthe drive instruction, the position and/or speed of the lens unit Lcalculated from the detection signals from the detection unit 285, thetemperature of the vibration-wave motor 201 measured by the temperaturemeasurement unit 286, individual differences in vibration-wave motors201, etc., and controls so that the lens unit L is positioned at thetarget position (timing T1 to T2 in FIG. 20).

If the frequency set in the oscillation unit 282 becomes a lowerfrequency wave than the holding frequency f0, the revolution speed ofthe vibration-wave motor 201 will become greater than zero. Since thevoltage application to the vibration-wave motor 201 is not made to stopwhen causing the vibration-wave motor 201 to stop, abnormal noise is notgenerated even when the vibration-wave motor 201 starts driving.

In Step S130, the control unit 281 judges whether the lens unit L hasreached the target position. The control unit 281 advances theprocessing to Step S120 in the case of Step S130 being negativelyjudged, and advances the processing to Step S140 in the case of StepS130 being positively judged.

In Step S140, the control unit 281 controls so as to set the holdingfrequency f0 in the oscillation part 282, and the signal of the holdingfrequency f0 is oscillated from the oscillation unit 282 timing T2 to T3in FIG. 20).

In Step S150, the control unit 281 judges whether a subsequent driveinstruction is being acquired. The control unit 281 advances theprocessing to Step S110 in the case of Step S150 being positivelyjudged, and advances the processing to Step S160 in the case of StepS150 being negatively judged.

In Step S160, the control unit 281 sets the phase difference of 0° inthe phase shifting unit 283, changes the phase difference between thesignal of the A-phase and the signal of the B-phase outputted by thephase shifting unit 283, and then ends the processing of FIG. 19. It isthereby controlled so that the rotational speed of the vibration-wavemotor 201 becomes zero according to the phase difference as shown inFIG. 16.

As shown in FIG. 17, the holding frequency f0 has a range of availablevalues. In Step S140, the effect obtained in the vibration-wave motor201 changes according to what value within the range the control unit281 sets the holding frequency f0 set in the oscillation unit 282. Thedifference in effects thereof will be explained using FIG. 21.

FIG. 21 is a graph exemplifying the frequency—vibration deformationcharacteristic of the vibrating body 261. FIG. 21 exemplifies theposition at which the natural frequency f9 of a 9th-order bendingvibration of the vibrating body 262 is 26 kHz, and exemplifies theposition at which the natural frequency f10 of the 10th-order bendingvibration is 32 kHz. Hereinafter, the natural frequency f9 of the9th-order bending vibration is abbreviated simply as natural frequencyf9, and the natural frequency f10 of the 10th-order bending vibration isabbreviated simply as natural frequency f10.

When the frequency of the drive signal is in the vicinity of the naturalfrequency f9 of the 9th-order bending vibration, a 9-peak progressivewave generates at the driving face 223 of the vibrating body 261. Then,when the frequency of the drive signal is in the vicinity of the naturalfrequency f10 of the 10th-order bending vibration, a 10-peak progressivewave generates at the driving face 223 of the vibrating body 261. Amongthe magnitudes of vibration of the vibrating body 261, the 9-peakprogressive wave component becomes smaller as the frequency distancesfrom the natural frequency f9. Similarly, among the magnitudes ofvibration of the vibrating body 261, the 10-peak progressive wavecomponent becomes smaller as the frequency distances from the naturalfrequency f10.

As mentioned in the foregoing, the piezoelectric body 261 b assumes anelectrode pattern that tends to cause a 9-peak progressive wave to beexcited, and the vibration-wave motor 201 has a better drive efficiencywhen using a 9-peak progressive wave than when using a 10-peakprogressive wave. For this reason, the magnitude of the vibration of the9-peak progressive wave in FIG. 21 is greater than the magnitude of thevibration of the 10-peak progressive wave.

In the case of the phase difference between the drive signals of the twophases being the same, the rotational direction of the 9-peakprogressive wave and the 10-peak progressive wave will be oppositedirections from each other. For example, in the case of the phasedifference between the drive signals of the two phases being +90°, whenthe frequency of the drive signal is 27 kHz, the moving body 262 rotatesas positive rotation, and when the frequency of the drive signal is 33kHz, the moving body 262 rotates as reverse rotation. When the frequencyis between the natural frequency f9 and the natural frequency f10, therotation of the moving body 262 according to 9-peak progressive wavecomponent and the rotation of the moving body 262 according to the10-peak progressive wave component cancel out each other.

(1) Case of holding frequency f0 being average value of naturalfrequency f9 and natural frequency f10. In the case of the holdingfrequency f0 being the average value of natural frequency f9 and naturalfrequency f10, e.g., a case of the holding frequency f0 being 29 kHz inthe example of FIG. 21, the magnitude of the vibration of the vibratingbody 261 becomes small. This is because, in the middle between thenatural frequency f₉ and the natural frequency f10, the 9-peakprogressive wave component and the 10-peak progressive wave componentdecrease together. Furthermore, the rotation of the moving body 262according to the 9-peak progressive wave component and the rotation ofthe moving body 262 according to the 10-peak progressive wave componentcancel.

Therefore, in the case of the holding frequency f0 being the averagevalue of the natural frequency f9 and natural frequency f10, since themoving body 262 will not distance from the vibrating body 261 due to themagnitude of the vibration of the vibrating body 261 being small,abnormal noise will not generate from collisions between the moving body262 and vibrating body 261. In addition, since the rotation of themoving body 262 according to the 9-peak progressive wave component andthe rotation of the moving body 262 according to the 10-peak progressivewave component cancel, the certainty of stopping rotation of the movingbody 262 increases.

(2) Case of holding frequency f0 being higher frequency than averagevalue of natural frequency f9 and natural frequency f10. In the case ofthe holding frequency f0 being higher frequency than the average valueof natural frequency f9 and natural frequency f10, i.e. a case of beingcloser to natural frequency f10 than natural frequency f9, the 10-peakprogressive wave component becomes dominant in the progressive wavegenerated by the vibrating body 262. The moving body 262 rotating basedon the 9-peak progressive wave component in Step S120 of FIG. 19 iscontrolled based on the 10-peak progressive wave component when thedrive frequency is changed to the holding frequency f0 in Step S140. Inother words, since the rotation according to the 10-peak progressivewave component has a rotational direction that is an opposite directionto the rotation according to the 9-peak progressive wave component, therotational direction of the moving body 262 in Step S140 becomes anopposite direction to the rotational direction during control in theimmediately previous Step S120. However, since the torque generatingfrom the vibration-wave motor 201 at this time is small, the fork 254,cam ring 253 and AF ring 252 do not rotate.

Therefore, in the case of there being a subsequent drive instruction inStep S150, when deciding to cause the moving body 262 to rotate in thereverse direction in the subsequent drive instruction, rattling betweenthe projecting part 255 a and fork 254 and rattling between the keygroove 253 a and fixed pin 252 a stop. It is thereby possible tosuppress mechanical collision noise when the moving body 262 actuallystarts to rotate in the reverse direction.

(3) Case of holding frequency f0 being lower frequency than averagevalue of natural frequency f9 and natural frequency f10. In the case ofthe holding frequency f0 being lower frequency than the average value ofnatural frequency f9 and natural frequency f10, i.e. a case of beingcloser to natural frequency f9 than natural frequency f10, the 9-peakprogressive wave component becomes dominant in the progressive wavegenerated by the vibrating body 262. In this case, the rotationaldirection of the moving body 262 in Step S140 is the same direction asthe rotational direction during control in the immediately prior StepS120. Therefore, in the case of there being a subsequent driveinstruction in Step S150, when deciding to cause the moving body 262 torotate in the same direction in the subsequent drive instruction,rattling between the projecting part 255 a and fork 254 and rattlingbetween the key groove 253 a and fixed pin 252 a stop. It is therebypossible to suppress mechanical collision noise when the moving body 262actually starts to rotate in the same direction.

In addition, since the holding frequency f0 is closer to naturalfrequency f9 when the above (1) and (2), the period of timing T2 to T3in FIG. 20 can be shortened when the above (1) and (2). The processingtime in drive control of the moving body 262 is thereby shortened, andthe stop accuracy of the moving body 262 rises.

As explained in the above (2), when driving in the opposite direction tothe immediately prior drive instruction with the subsequent driveinstruction, it is better to set the holding frequency f0 to a higherfrequency than the average frequency of natural frequency f9 and naturalfrequency f10. In addition, as explained in the above (3), when drivingin the same direction as the immediately prior drive instruction withthe subsequent drive instruction, it is better to set the holdingfrequency f0 to a lower frequency than the average frequency of naturalfrequency f9 and natural frequency f10.

FIG. 22 is a flowchart relating to the processing of Step S140 in FIG.19. In the processing of FIG. 22, the holding frequency is appropriatelyset based on the subsequent drive instruction executed after executing adrive instruction.

In Step S141, the control unit 281 judges whether to acquire asubsequent drive instruction. The control unit 281 advances theprocessing to Step S142 in the case of Step S141 being positivelyjudged, and advances the processing to Step S143 in the case of StepS141 being negatively judged.

In Step S142, the control unit 281 judges whether the subsequent driveinstruction is an instruction to cause the moving body 262 to rotate inthe same direction as the drive instruction completed immediately prior.The control unit 281 advances the processing to Step S145 in the case ofStep S142 being positively judged, and advances the processing to StepS144 in the case of Step S142 being negatively judged.

In Step S143, the control unit 281 sets the holding frequency f0 to theaverage value of natural frequency f9 and natural frequency f10. Effectslike those explained in the above (1) are thereby obtained. In StepS144, the control unit 281 sets the holding frequency f0 to a frequencythat is higher frequency than the average value of natural frequency f9and natural frequency f10, and lower frequency than natural frequencyf10. Effects like those explained in the above (2) are thereby obtained.In Step S145, the control unit 281 sets the holding frequency f0 to afrequency that is lower frequency than the average value of naturalfrequency f9 and natural frequency f10, and higher frequency thannatural frequency f9. Effects like those explained in the above (3) arethereby obtained.

In Step S146, the control unit 281 sets the holding frequency f0 set inSteps S143 to S145 in the oscillation part 282.

The following operational effects are obtained according to theembodiment explained above. The drive apparatus 290 driving the lensunit L in the lens barrel 202 includes the drive circuit 280 andvibration-wave motor 201. The drive circuit 280 generates the drivesignals of the A-phase and B-phase. The vibration-wave motor 201includes the vibrating body 261 and moving body 262. The vibrating body261 includes the piezoelectric body 261 b to which the drive signals ofthe A-phase and B-phase generated by the drive circuit 280 are applied,thereby causing a progressive wave to be generated at the driving face223 of the elastic body 261 a by the vibration of this piezoelectricbody 261 b, and causing a drive force for driving the moving body 262under pressurized contact to generate. The drive circuit 280 has thecontrol unit 281 that sets the frequency and phase difference of thedrive signals of the A-phase and B-phase, changes the phase differenceset in the phase shifting unit 283 (Step S110 of FIG. 19) after settingthe frequency oscillated by the oscillation part 282 to the holdingfrequency f0 when changing the driving direction of the moving body 262.By configuring in this way, it is possible to suppress the generation ofabnormal noise since driving of the moving body 262 is made to stopaccording to the control of drive frequency, upon switching the drivingdirection of the moving body 262 by the drive apparatus 290.

When changing the phase difference while the moving body 262 is driving,the rotation of the moving body 262 becomes unstable, and there isconcern over abnormal noise generating by collision between the movingbody 262 and vibrating body 261. However, there is no concern over suchabnormal noise generating so long as configuring so as to control thephase difference between the drive signals of the A-phase and B-phase ina state in which driving of the moving body 262 is stopped, as in thepresent invention.

In addition, when changing the phase difference while the moving body262 is driving, the moving body 262 may be temporarily driven at lowspeed; however, the rotational unevenness of the moving body 262increases during low speed driving, and thus there is concern over nolonger being able to ensure stop precision. However, such an increase inrotational unevenness does not occur, and thus there is no concern overno longer being able to ensure stop precision, so long as configuring soas to control the phase difference between the drive signals of theA-phase and B-phase in a state in which driving of the moving body 262is stopped, as in the present invention.

The third embodiment explained above can be implemented by modifying inthe following way.

MODIFIED EXAMPLE 4

In the above-mentioned embodiment, the piezoelectric body 261 b isconfigured to be in an electrode pattern for which a 9-peak progressivewave tends to generate, and generates a 9-peak progressive wave or10-peak progressive wave at the driving face 223 of the vibrating body261. However, the progressive wave generated by the vibrating body 261is not limited to a 9-peak progressive wave. The present invention maybe configured to cause an nth-order bending vibration to generate fromany n-peak progressive wave at the driving face 223.

MODIFIED EXAMPLE 5

In the above-mentioned embodiment, the phase difference between drivesignals of the A-phase and B-phase is not controlled while performingdrive control of the lens unit L by controlling the frequency set in theoscillation part 282. However, within a range in which abnormal noisefrom collisions between the moving body 262 and vibrating body 261 andan increase in rotational unevenness of the moving body 262 can beignored, the phase difference of the drive signals of the A-phase andB-phase may be controlled also while performing drive control of thelens unit L by controlling the frequency set in the oscillation part282.

Fourth Embodiment

Hereinafter an embodiment of a electric camera 301 according to thepresent invention will be explained in detail while referencing theattached drawings. FIG. 23 is a view illustrating a electric camera 301of a fourth embodiment of the present invention. The electric camera 301is a camera capable of still image and moving image photography, isconfigured from a lens barrel 320, which is an imaging optical system,an imaging element 330, an AFE (Analog Front End) circuit 360, an imageprocessing unit 370, a voice detection unit 380, an operation member390, a CPU 400, buffer memory 410, a recording interface 420, memory430, and a monitor 440, and is connectable with a PC 450 of an externaldevice.

The lens barrel 320 is configured from a plurality of optical lens unitsL, and causes a subject image to focus on a light receiving surface ofthe imaging element 330. FIG. 23 illustrates the plurality of opticallens units L by simplifying as a single lens. Among these optical lensunits L, a third lens unit L3 for AF described later (illustrated inFIG. 23) is driven by a vibration-wave motor 310.

The imaging element 330 is configured by a CMOS image sensor and thelike in which light-receiving elements are aligned in two-dimensions onthe light receiving surface. The imaging element 330 generates an analogimage signal by photoelectrically converting the subject image from abeam having passed through the lens barrel 320.

The analog image signal is inputted to the AFE circuit 360. The AFEcircuit 360 performs gain adjustment (signal amplification according tothe ISO sensitivity) on the analog image signal. More specifically, theimaging sensitivity is changed within a predetermined range according toa sensitivity setting instruction from the CPU 400. The AFE circuit 360converts the image signal after analog processing by a built-in A/Dconversion circuit into digital data. This digital data is inputted tothe image processing unit 370.

The image processing unit 370 performs various image processing ondigital image data. The buffer memory 410 temporarily records image datain pre-process or post-process of the image processing by the imageprocessing unit 370.

The voice detection unit 380 is configured from a microphone and asignal amplifier, mainly detects and captures a voice from the subjectdirection during moving image photograph, and transmits this data to theCPU 400.

The operation member 390 indicates mode dials, the arrow keys, a selectbutton and a release button, and sends an operation signal according tothe respective operations to the CPU 400. The setting of still imagephotography and moving image photograph is set by way of the operationmember 390.

The CPU 400 unifyingly controls actions performed by the electric camera301 by executing a program stored in the ROM that is not illustrated.For example, AF (autofocus) operation control, AE (automatic exposure)operation control, and auto white balance control, etc. are performed.

The recording interface 420 has a connector that is not illustrated, arecording medium such as a memory card 421 is connected to thisconnector, and performs the writing of data to the connected recordingmedium or reading of data from the recording medium.

The memory 430 records a sequence of image data subjected to imageprocessing. Images corresponding to a moving image are captured in theelectric camera 301 of the present embodiment. The monitor 440 isconfigured by a liquid crystal panel, and displays an operation menu,still image, moving image, etc. according to an instruction from the CPU400.

Next, the lens barrel 320 will be explained. FIG. 24 is a viewillustrating the lens barrel 320 according to the fourth embodiment ofthe present invention. FIG. 25 is a view illustrating a vibrator 311 ofthe vibration-wave motor 310 according to the fourth embodiment of thepresent invention. The lens barrel 320 includes an outer fixed cylinder331 that covers the outer circumferential part of the lens barrel 320,an inner fixed cylinder 332 that is positioned more to the innercircumferential side than the outer fixed cylinder 331, and furtherincludes the vibration-wave motor 310 between the outer fixed cylinder331 and the inner fixed cylinder 332.

From a subject side, a first lens unit L1, a second lens unit L2, athird lens unit L3, which is an AF lens retained in an AF ring 334, anda fourth lens unit L4 are arranged in the inner fixed cylinder 332. Thefirst lens unit L1, second lens unit L2 and fourth lens unit L4 arefixed to the inner fixed cylinder 332. The third lens unit L3 isconfigured to be moveable relative to the inner fixed cylinder 332 byway of the AF ring 334 moving.

As shown in FIG. 24, the vibration-wave motor 310 includes a vibrator311, a moving element 315, a pressurizing member 318, etc., and assumesa form fixing the vibration 311 side thereof and rotationally drivingthe moving element 315. The vibrator 311 will be explained. As shown inFIG. 25, the vibrator 311 is configured from an electro-mechanicalconversion element exemplified as a piezoelectric element orelectrorestrictive element that converts electrical energy to mechanicalenergy (hereinafter referred to as piezoelectric body 313), and anelastic body 312 joined with the piezoelectric body 313. Although madeso that a progressive wave generates in the vibrator 311, a 9-peakprogressive wave is generated as one example in the present embodiment.

The elastic body 312 consists of a metal material having a largeresonance sharpness, and the shape thereof is an annular shape Theopposing face of the elastic body 312 to which the piezoelectric body313 is joined forms a comb-teeth portion 312 in which grooves are cut,and the tip end face of the projecting portions (parts without grooves)are a driving face and are under pressurized contact with the movingelement 315. The vibration-wave motor 310 drives the third lens unit L3by driving the moving element 315 using the drive force generated at thedriving face by way of the excitation of the piezoelectric body 313. Thereason for cutting the grooves is to bring the neutral plane of theprogressive wave as near as possible to the piezoelectric body 313 side,thereby making the amplitude of the progressive wave at the driving faceamplified. The portions not cut with grooves are called base parts 312 bin the present embodiment.

The piezoelectric body 313 is joined at the opposing face of the baseparts 312 b than the comb-teeth part 312 a. Lubricity surface treatmentis made on the driving face of the elastic body 312. The piezoelectricbody 313 is divided into the two phases (A-phase, B-phase) along thecircumferential direction, and in each phase, elements for which thepoles are alternating every ½ wavelength are aligned, and a ¼ wavelengthinterval is open between the A-phase and B-phase.

The piezoelectric body 313 is generally configured from a material likelead zirconate titanate, which is called by the abbreviation PZT;however, due to environmental problems in recent years, it may also beconfigured from potassium sodium niobate, potassium niobate, sodiumniobate, barium titanate, bismuth sodium titanate, bismuth potassiumtitanate, etc., which are lead-free materials.

As shown in FIG. 24, below the piezoelectric body 313, a non-wovenfabric 316, pressure plate 317 and pressurizing member 318 are arranged.The non-woven fabric 316 is exemplified as felt, is arranged below thepiezoelectric body 313, and makes so that vibration of the vibrator 311does not convey to the pressure plate 317 or pressurizing member 318.

The pressure plate 317 is made so as to receive the pressure of thepressurizing member 318. The pressurizing member 318 is configured froma disk spring, is arranged below the pressure plate 317, and causes anapplied pressure to generate. In the present embodiment, although thepressurizing member 318 is a disk spring, it does not need to be a diskspring, and may be a coil spring or a wave spring. The pressurizingmember 318 is retained by a pressing ring 319 being fixed to a fixedmember 314.

The moving element 315 consists of a light metal such as aluminum, andsurface treatment of a sliding material or the like for abrasionresistance improvement is done on the surface 315 a of sliding face(refer to FIG. 25).

In order to absorb vibrations in the longitudinal direction of themoving element 315, a vibration absorbing member 323 formed from rubberor the like is arranged on the moving element 315, and thereon, anoutput transfer member 324 is arranged.

The output transfer member 324 is made so as to define the pressurizingdirection and radial direction by way of a bearing 325 provided to thefixed member 314, whereby the pressurizing direction and radialdirection of the moving element 315 are defined.

The output transfer member 324 has a projecting part 324 a and,therefrom, a fork 335 connecting to a cam ring 336 fits. The cam ring336 is rotated along with the rotation of the output transfer member324.

A key groove 337 is cut obliquely relative to the circumferentialdirection in the cam ring 336. In addition, a fixed pin 338 is providedat the outer circumferential side of the AF ring 334. The fixed pin 338fits into the key groove 337, and by the cam ring 336 rotationallydriving, the AF ring 334 is driven in the optical axis advancingdirection, and makes it possible to stop at a desired position.

The pressing ring 319 is attached by a spring to the fixed member 314.By attaching the pressing ring 319 to the fixed member 314, it ispossible to configure from the output transfer member 324, movingelement 315, vibrator 311 until the pressurizing member 318 as one motorunit.

Next a drive apparatus 340A will be explained. FIG. 26 is a blockdiagram illustrating the drive apparatus 340A of the vibration-wavemotor 310. The drive apparatus 340A is provided to a substrate 340(refer to FIG. 24). The drive apparatus 340A is connected to thevibration-wave motor 310 as shown in FIG. 26, and receives a revolutionspeed of the vibration-wave motor 310 from the rotation detection unit345 provided to the vibration-wave motor 310, as well as performingcontrol of the vibration-wave motor 310.

The drive apparatus 340A includes a drive control unit 341, oscillationpart 342, phase shifting unit 343, and amplifier 344. In addition, therotation detection unit 346 attached to the vibration-wave motor 310, acontrast detection unit 339 and a photography setting unit 347 that canselect moving image photography mode or a still image photography modeare connected to the drive control unit 341 of the drive apparatus 340A.

The drive control unit 341 controls driving of the vibration-wave motor310 based on a drive command from the CPA 340 inside of the lens barrel320 or the main body of the camera 301. The oscillation part 342generates a drive signal of a desired frequency according to the commandof the drive control unit 341. The drive signal is asymmetrically shapedin the + direction and − direction based on zero potential. The phaseshifting unit 343 divides the drive signal generated by the oscillationpart 342 into two drive signals of different phases. The amplifier 344boosts the two drive signals divided by the phase shifting unit 343 todesired voltages, respectively. The two drive signals from the amplifier344 are transmitted to the vibration-wave motor 310, whereby aprogressive wave generates at the vibrator 311 by way of the applicationof these two drive signals, and the moving element 315 is driven.

The rotation detection unit 346 is configured from an optical encoder,magnetic encoder, or the like, detects the position and/or speed of adriven object driven by the driving of the moving element 315, andtransmits the detection value to the drive control unit 341 as anelectrical signal. The contrast detection unit 339 detects the contrastof the subject image. The contrast detection unit 339, for example,determines if the subject is within a current range of focal positionsof the lens, is in the + direction, is in the − direction, and beingdisplaced to what extent. The contrast detected by the contrastdetection unit 339 is transmitted to the drive control unit 341 as anelectrical signal.

The drive control unit 341 controls the driving of the vibration-wavemotor 310 based on the drive command from the CPU 400 inside of the lensbarrel 320 or of the main body of the camera 301. When receiving thedetection signal from the rotation detection unit 346, the drive controlunit 341 obtains positional information and speed information based onthis value, and controls the frequency of the oscillation part 342,phase difference of the phase shifting unit 343 and voltage of theamplifier 344, so as to position at the target position.

In addition, the drive control unit 341 makes so that the photographyinformation (still image mode/moving image mode, etc. selected by way ofthe photography setting unit 347) is transferred by the lens or camera.The drive control unit 341 smoothly controls the frequency and phasedifference of the drive signals based on this photography informationfrom the lens or camera. More specifically, in a case of the photographysetting unit 347 having selected moving image photography mode, thedrive control unit 341 switches the phase difference of the two drivesignals, as well as switching the frequency of the two drive signals tocorrespond to the switched phase difference, while maintaining thevoltages of the two drive signals to be constant, whereby the speed ofthe vibration-wave motor 310 is variable. In addition, the drive controlunit 341 switches the frequencies of the two drive signals based on thecontrast detected by the contrast detection unit 339.

In order to simplify the explanation in the present embodiment, aconfiguration is established in which the information of the contrastdetection unit 339 and information of the photography setting unit 347are transmitted directly to the drive control unit 341; however, it isnot to be limited thereto. For example, it may be configured so that theinformation of the contrast detection unit 339 and/or information of thephotography setting unit 347 is temporarily conveyed to the CPU of thecamera, and subsequently conveyed to the drive control unit 341 in thelens.

Next, driving and control of the vibration-wave motor 310 by the driveapparatus 340A will be explained. First, the target position istransmitted from the CPU 400 inside the lens barrel 320 or the main bodyof the camera 301 to the drive control unit 341. The drive signalgenerates from the oscillation part 342, this signal is split into twodrive signals of 90° different phase by the phase shifting unit 343, andis amplified to a desired voltage by the amplifier 344. The drivecontrol unit 341 provides two drive signals to the vibration-wave motor310.

The two drive signals are applied to the piezoelectric body 313 of thevibration-wave motor 310, the piezoelectric body 313 is excited, and a9-peak bending vibration generates at the elastic body 312 according tothis excitation. The piezoelectric body 313 is divided into the A-phaseand B-phase, and the two drive signals are respectively applied to theA-phase and B-phase. The 9-peak bending vibration generating from theA-phase and the 9-peak bending vibration generating from the B-phaseform so as to have a positional phase shifted by ¼ wavelength, and theA-phase drive signal and B-phase drive signal are shifted by 90° phase;therefore, the two bending vibrations are combined to form a 9-peakprogressive wave. A +90° or −90° value of the phase difference is anideal value, and although the shape of the progressive wave is disturbedat an intermediate value thereof, a progressive wave is produced.Elliptic motion occurs at the crests of the wave of the progressivewave. Therefore, the moving element 315 under pressurized contact withthe driving face is driven by the friction from this elliptic motion.

An optical encoder is arranged at the driven body driven by the drivingof the moving element 315, and from this, an electrical pulse generates,which is transmitted to the drive control unit 341. The drive controlunit 341 becomes able to obtain the current position and current speedbased on this signal, and controls the drive frequency of theoscillation part 342 based on this positional information, speedinformation and target position information.

In addition, in the case of driving the AF ring 334 in the positivedirection, the phase difference between the two drive signals (frequencyvoltage signals) may be set to a + value, e.g., +90°, by the phaseshifting unit 343, and in the case of driving the AF ring 334 in thereverse direction, the phase difference between the two drive signals(frequency voltage signals) may be set to a − value, e.g., −90°, by thephase shifting unit 343.

On the other hand, based on the information as to the currentphotography mode being the still image mode/moving image mode, the drivecontrol unit 341 controls the drive frequency of the oscillation part342 in the case of being the still image mode, and controls the drivefrequency of the oscillation part 342 and the phase difference of thephase shifting unit 343 in the case of being the moving image mode. Inparticular, in the wobbling operation causing the third lens unit L3 forAF to move back and forth in small motions, the phase difference ischanged to control the position and speed. Wobbling operation is anoperation causing the lens for AF to move back and forth in smallmotions to make the focal position follow the subject.

FIG.27A is a graph showing the relationship of rotational speed relativeto the phase difference of the drive signals of the vibration-wavemotor, and FIG.27B is a graph showing the relationship of the rotationalspeed relative to the drive frequency of the vibration-wave motor. Asshown in FIG.27A, the rotational speed reaches a maximum speed ofpositive rotation at the phase difference of the two drive signals of+90°, and reaches a maximum speed of reverse rotation at the phasedifference of the two drive signals of −90°, and the intermediate phasedifferences thereof indicate intermediate speed values. In addition, asshown in FIG.27B, when the drive frequency is decreased, the rotationalspeed increases, and when increasing the frequency, the rotational speeddeclines, and reaches O. For example, when setting the phase differenceof the two drive signals to +90°, the rotational speed increases withsmaller drive frequency.

FIRST OPERATION EXAMPLE

Next, a first operation example of a fourth embodiment of the presentinvention will be explained based on a timing chart for the driving ofthe vibration-wave motor 310 by the drive apparatus 340A in the case ofthe moving image mode being selected. FIG. 28 is a timing chartillustrating operations of the first operation example of the driveapparatus 340A according to the fourth embodiment. In the case of themoving image mode being selected in the present embodiment, therelationships of the drive frequency, drive voltage, phase difference,and rotational speed of the vibration-wave motor 310 will be explainedin sequential order. In the present embodiment, in the case of themoving image mode being selected, the drive frequency is set to f0(maximum frequency), and the drive voltage is set to V0 (minimumvoltage).

At t0, the drive apparatus 340A sets the phase difference of the twodrive signals to +90°, and turns ON the drive signal.

At t1, the drive apparatus 340A causes the drive voltage to increase.

At t2, the drive apparatus 340A sets the drive voltage to V1.

At t3, the drive apparatus 340A starts sweeping the drive frequency fromthe maximum frequency f0.

At t4′ immediately after t4, the drive apparatus 340A starts driving thevibration-wave motor 310 in the middle of the drive frequency beingswept, and sets the drive frequency to frequency f1.

In the case of being the moving image mode, wobbling operation isperformed to make the third lens unit L3 for AF to move back and forthin small motions. In the case of the present embodiment, it isestablished at an interval of 20 Hz. At t4 to t5, the drive apparatus340A sets the phase difference of the two drive signals to +90° to causerotation as positive rotation, and makes the speed V. At t5 to t6, thedrive apparatus 340A sets the phase difference of the two drive signalsto 0°, and the contrast at position Wbe is detected by the contrastdetection unit 339. At t6 to t7, the drive apparatus 340A sets the phasedifference of the two drive signals to −90°, setting the frequency tof2, which is smaller than f1, causing to reverse-rotationally drive atthe frequency f2, and the speed is set to −2V (twice V). The reason forsetting the speed during reverse rotation of the wobbling operation totwice the positive rotation is that the movement amount of the lensposition is twice.

At t7 to t8, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°, and detects the contrast at position Waf. At t8to t9, the drive apparatus 340A sets the phase difference of the twodrive signals to +90°, causing positive rotational driving at frequencyf1, and makes the speed V. At t9 to t10, the drive apparatus 340A setsthe phase difference of the two drive signals to 0°, and detects thecontrast at W₀ position.

Wobbling operation is performed by repetition hereinafter. One cycle ofthe wobbling operation (for example, between t4 and t10) is an intervalof 20 Hz (=approx. 50 msec). Between t9 and t10, the position of thesubject is calculated from the detection results of contrast of positionWbe, position Waf and position W₀ to decide the drive frequency of onecycle of the next wobbling operation. In other words, based on thecontrast of a predetermined one cycle in the wobbling operation detectedby the contrast detection unit 339, the drive control unit 341 switchesthe frequency of the two drive signals of a subsequent one cycle to apredetermined one cycle, so that the focal position of the third lensunit L3 for AF follows the subject.

The deciding parameters are the frequency fs between t10 and t11, thefrequency fb between t12 and t13, and the frequency fs2 between t14 andt15. For example, in the results of contrast detection in one cycle ofthe wobbling operation between t4 and t10, in the case of beingdetermined that the subject is between the wobbling amplitude (+1 to−1), in one cycle of the subsequent wobbling operation, the wobblingamplitude is set to +1 to −1 and defines frequency fs=f₁, frequencyfb=f2 and frequency fs2=f₁. It should be noted that the subjectdetection results in FIG. 28 are configured so as to indicate bettercontrast with a larger value (good contrast=in focus=defined as 1, andindicating a smaller numerical value as going more out of focus).

In addition, as another case, in the case of being determined that thesubject is in the + direction from the current lens position as a resultof contrast detection in one cycle of the wobbling operation between t17to t22, one cycle of the subsequent wobbling operation defines the speedat t22 to t23 as 3V, and performs movement of the lens at three timesthe wobbling amplitude. In this case, it defines frequency fs=f3(frequency even smaller than f2), frequency fb=f2, and frequency fs2=f1.

Furthermore, as another case, in the case of being determined that thesubject is greatly in the + direction from the current lens position asa result of contrast detection in one cycle of the wobbling operationbetween t40 and t45, one cycle of the subsequent wobbling operationperforms movement of the lens at three times the wobbling amplitude,with the speed between t40 and t41 as 4V. In this case, it definesfrequency fs=f4 (frequency even smaller than f3), frequency fb=f2, andfrequency fs2=f1.

Herein, when trying to drive the lens, there is a possibility of aproblem arising in that a very small sound during the drive signal ONwhen starting the drive signal to the vibration-wave motor is picked upby the microphone that detects voices during moving image photography.The cause thereof is from sound of various frequencies generating fromthe stator (vibrator) at the moment when the drive signal applied to thevibration-wave motor changes step-wise from 0V to a certain voltage, andthe audible sound thereof being picked up with the voices. The soundpressure of this sound depends on the magnitude of voltage, and in thecase of the voltage of the drive signal being small, a trend is observedof the sound pressure declining.

In this aspect, the moment when the drive signal is ON, the voltagevalue of the drive signal voltage decreases, and a countermeasure istaken by setting the sound pressure of the sound generated from thestator (vibrator) to no more than the sensitivity of the microphone, andafter the drive signal is ON, returning the drive voltage to a normalvoltage (rated voltage).

However, it is necessary to perform the wobbling operation to cause theAF lens to move forward and backward during moving image photography,and between when driving in the positive direction and when driving inthe reverse direction, it temporarily stops, and the phase differencemust change. In this case, in order to prevent a small noise fromgenerating from the stator (vibrator), by a conventional control method,the phase difference between the two drive signals is set to +90°, andthe drive voltage is changed from V₀ to V₁ to cause the AF ring 34 topositively rotationally drive. Next, the drive voltage is changed fromV₁ to V₀, and the phase difference between the two drive signals is setto −90°. Furthermore, the drive voltage is changed from V₀ to V₁ tocause the AF ring 34 to reverse rotationally drive. Next, the drivevoltage is changed from V₁ to V₀, and the phase difference between thetwo drive signals is set to +90°. Since repetition is performedhereinafter, it becomes a very complicated operation.

In the present embodiment, it is configured so as to perform thewobbling operation by switching the phase difference of the two drivesignals between three stages (90°, 0°, −90°), and the setting afrequency according to this phase difference, while maintaining thevoltage to be fixed. It should be noted that switching of the phasedifference of the two drive signals is ideally continuously switchingthe phase difference gradually for very small sound generationprevention.

By configuring in this way, silent driving becomes possible withoutrequiring complicated driving as is conventionally.

It should be noted that, in the case of the still image mode beingselected, the voltage is set to the rated voltage V₁ and then the drivesignal is turned ON to perform sweeping start of the drive frequency, asis conventionally. In addition, in the case of the still image mode,positional and/or speed control becomes control according to the drivefrequency or drive voltage due to not being required to perform wobblingoperation.

It should be noted that the sound during drive signal ON is small anddetected as sound due to the voice microphone being provided very nearthe vibration-wave motor; however, it is sound that can almost not beheard by the operating person.

Hereinafter, operations of a first operation example of the driveapparatus 340A according to the fourth embodiment will be explainedbased on the flowchart.

FIG. 29 is a flowchart illustrating operations of the first operationexample of the drive apparatus 340A according to the fourth embodiment.

First, driving of the lens is started.

In S501, the drive apparatus 340A determines whether being the movingimage mode or being the still image mode. In the case of being themoving image mode, the processing advances to Step S502. The driveapparatus 340A advances to Step S601 in the case of being the stillimage mode, and performs the driving operation during still imagephotography without performing the wobbling operation.

In Step S502, the drive apparatus 340A sets the voltage to V0, as wellas setting the phase difference of the two drive signals to +90°.

In Step S503, the drive apparatus 340A turns the drive signal ON.

In Step S504, the drive apparatus 340A causes the voltages of the twodrive signals increase.

In Step S505, the drive apparatus 340A sets the voltages of the twodrive signals to V₁.

In Step S506, the drive apparatus 340A starts sweeping of the frequency,and sets the frequency to f1.

The moving element 315 thereby drives, and the AF ring 334 is driven inthe positive direction.

In Step S507, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°. Driving of the moving element 315 therebystops.

In Step S508, the drive apparatus 340A detects the position Wbe andcontrast.

In Step S509, the drive apparatus 340A sets the frequency to f2.

In Step S510, the drive apparatus 340A sets the phase difference of thetwo drive signals to −90°.

The moving element 315 thereby drives, and the AF ring 334 is driven inthe reverse direction.

In Step S511, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°. Driving of the moving element 315 therebystops.

In Step S512, the drive apparatus 340A detects the position Waf andcontrast.

In Step S513, the drive apparatus 340A sets the frequency to f1.

In Step S514, the drive apparatus 340A sets the phase difference of thetwo drive signals to 90°.

The moving element 315 thereby drives, and the AF ring 334 is driven inthe positive direction.

In Step S515, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°.

Driving of the moving element 315 thereby stops.

In Step S516, the drive apparatus 340A detects the position W0 andcontrast.

In Step S517, the drive apparatus 340A calculates the subject positionaccording to the position Wbe, position Waf, position W0 and respectivecontrast information.

In Step S518, the frequencies fs and fb are calculated.

In Step S519, the drive apparatus 340A sets the phase difference of thetwo drive signals to +90°.

The drive apparatus 340A sets the frequency to fs. For example, in theresults of detecting contrast in one cycle of the wobbling operationbetween t17 and t22 in FIG. 28, when determined that the subject is inthe + direction from the current lens position, one cycle of thesubsequent wobbling operation sets f3 (frequency even smaller than f2).The moving element 315 thereby drives, and the AF ring 334 is driven inthe positive direction.

In Step S520, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°. Driving of the moving element 315 therebystops.

In Step S521, the drive apparatus 340A detects the position Wbe andcontrast.

In Step S522, the drive apparatus 340A sets the frequency to fb. Forexample, in the contrast detection results in one cycle of the wobblingoperation between t17 and t22 in FIG. 28, the drive apparatus 340A setsthe drive frequency to f2.

In Step S523, the phase difference of the two drive signals is set to−90°. The moving element 315 thereby drives, and the AF ring 334 isdriven in the reverse direction.

In Step S524, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°. Driving of the moving element 315 therebystops.

In Step S525, the drive apparatus 340A detects the position Waf andcontrast.

In Step S526, the drive apparatus 340A sets the frequency to fs2 (=f1).

In Step S527, the drive apparatus 340A sets the phase difference of thetwo drive signals to 90°. The moving element 315 thereby drives, and theAF ring 334 is driven in the positive direction.

In Step S528, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°. Driving of the moving element 315 therebystops.

In Step S529, the drive apparatus 340A detects the position W0 andcontrast.

In Step S530, the drive apparatus 340A detects the subject positionaccording to the position Wbe, position Waf, position W0 and respectivecontrast information.

In Step S531, the drive apparatus 340A determines whether driving of theAF ring 334 is finished.

In the case of driving of the AF ring 334 not being finished, theprocessing returns to Step S518, and performs the subsequent wobblingoperation. In the case of there being a photography end command andmaking stop when driving finishes, phase difference switching control isfinished, and the motion of the vibration-wave motor is stopped bysweeping the frequency to the high frequency side to f0. Then, thevoltage is gradually decreased from V1 to V0, and thereafter, the drivesignal is turned OFF.

In the present embodiment, the subject position is estimated bydetecting the contrast of three places of the lens position in StepsS519 to S530, and the calculation of the frequencies fs and fb is donein Step S518 according to this information. By switching the phasedifference between the A-phase and B-phase in three stages (90°, 0°,−90°) and setting the three drive frequencies of frequencies fs, fb andfs2, wobbling operation of the vibration-wave motor 10 is made possible.

SECOND OPERATION EXAMPLE

Next, a second operation example according to the fourth embodiment ofthe present invention will be explained. In the second operationexample, since the configurations of the lens barrel, vibration-wavemotor and drive apparatus 340A are the same as the first operationexample, explanations thereof will be omitted. The first operationexample and second operation example differ in the operations within thedrive apparatus 340A. The second operation example is a case of theposition of the subject moving to the + direction of the lens position,and then from midway, moving in one direction.

Driving of the vibration-wave motor 310 by the drive apparatus 340A ofthe second operation example will be explained based on the timingchart. FIG. 30 is a timing chart illustrating operations of the secondoperation example of the drive apparatus 340A according to the fourthembodiment of the present invention. The second operation example willbe explained in the case of the moving image mode being selected, inchronological order for the behavior in the case of the position of thesubject moving in the + direction of the lens position, and from midway,moving in one direction.

In the present embodiment, in the case of the moving image mode beingselected, the drive frequency is set to f0 (maximum frequency), and thedrive voltage is set to V0 (minimum voltage).

At t0, the drive apparatus 340A sets the phase difference of the twodrive signals to +90°, and turns the drive signal ON.

At t1, the drive apparatus 340A causes the drive voltages of the twodrive signals to increase.

At t2, the drive apparatus 340A sets the drive voltages of the two drivesignals to V₁.

At t3, the drive apparatus 340A starts sweeping of the drive frequencyfrom the maximum frequency f0.

At t4′ immediately after t4, the drive apparatus 340A starts driving ofthe vibration-wave motor 310 in the middle of the drive frequency beingswept, and then sets the drive frequency to frequency f1.

In the case of the moving image mode, the wobbling operation to causethe AF lens to move back and forth in small motions is performed. In thecase of the present embodiment, the interval of 20 Hz is established.

At t4 to t5, the drive apparatus 340A sets the phase difference of thetwo drive signals to +90° to cause to rotate as positive rotation, andmake the speed V.

At t5 to t6, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°, and detects the contrast at position Wbe.

At t6 to t7, the drive apparatus 340A sets the phase difference of thetwo drive signals to −90° to reverse rotationally drive at the frequencyf2, and make the speed −2V (twice V). In proportion to increasing speed,the frequency is set to f2, which is smaller than f1.

The reason for setting the speed during reverse rotation in the wobblingoperation to twice the positive rotation is that the movement amount ofthe lens position is twice.

At t7 to t8, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°, and detects the contrast at position Waf.

At t8 to t9, the drive apparatus 340A sets the phase difference of thetwo drive signals to +90° to positive rotationally drive at thefrequency f1, and makes the speed V.

At t9 to t10, the drive apparatus 340A sets the phase difference of thetwo drive signals to 0°, and detects the contrast at position W0.

Wobbling operation is performed by repetition hereinafter. One cycle ofthe wobbling operation (for example, between t4 and t10) is an intervalof 20 Hz (=approx. 50 msec)

Between t9 and t10, the position of the subject is calculated from thedetection results of contrast at position Wbe, position Waf and positionW0 to decide the next wobbling operation.

The deciding parameters are the frequency fs between t10 and t11, thefrequency fb between t12 and t13, and the frequency fs2 between t14 tot15.

For example, in the results of contrast detection in one cycle of thewobbling operation between t4 and t10, in the case of being determinedthat the subject is between the wobbling amplitude (+1 to −1), in onecycle of the subsequent wobbling operation, the wobbling amplitude isset as +1 to −1 and defines frequency fs=f1, frequency fb=f2 andfrequency fs2=f1.

It should be noted that the subject detection results in FIG. 30 areconfigured so as to indicate better contrast with a larger value (goodcontrast=in focus=defined as 1, and indicating a smaller numerical valueas going more out of focus).

In addition, in the case of the subject moving to the + direction of thelens, for example, in the case of being determined that the subject isin the + direction from the current lens position as a result ofcontrast detection in one cycle of the wobbling operation between t10and t16, one cycle of the subsequent wobbling operation defines thespeed at t16 to t17 as 3V, and performs movement of the lens at threetimes the wobbling amplitude. In this case, it defines frequency fs=f3(frequency even smaller than f2), frequency fb=f2, and frequency fs2=f1.

Next, in the case of the subject moving from the + direction to the −direction, if determined that the subject is greatly in the − directionfrom the current lens position as a result of contrast detection in onecycle of the wobbling operation between t22 and t27, one cycle of thesubsequent wobbling operation performs movement of the lens at fourtimes the wobbling amplitude, with the speed 4V between t30 and t31. Inthis case, it defines frequency fs=f1, frequency fb=f4 (frequency evensmaller than f3), and frequency fs2=f1.

Basically, it is the same as the explanation for the logic and theflowchart illustrated in FIG. 28 and FIG. 29, as in the aforementionedfirst operation example. In other words, in the wobbling operationduring moving image photography, the subject position is estimated bydetecting the contrast at three places of the lens position, and thefrequencies fs and fb are calculated according to this information.Then, by switching the phase difference between the A-phase and B-phasein three stages (approx. 90°, 0°, −90°) and setting the three drivefrequencies of frequencies fs, fb and fs2, it is possible to handle botha case of the subject moving in the + direction of the lens midway, anda case of moving in the − direction.

In addition, in the case of being determined that the subject is greatlyshifting from the current position, focusing on the subject is madepossible by inserting suitable values for the frequencies fs and fb (bysetting to frequency values far smaller than f4 in FIG. 28 or FIG. 30)

The following effects are possessed by the present embodiment above.

(1) In a case of the photography setting unit 347 having selected themoving image photography mode, the phase difference of the two drivesignals is switched, as well as the frequency of the two drive signalsbeing switched to correspond to the switched phase difference, whilemaintaining the voltages of the two drive signals to be constant,whereby the speed of the vibration-wave motor 310 can be changed. It isthereby possible to decrease the operating noise of the vibration-wavemotor 310 during moving image photography, without performingcomplicated drive control.

(2) Based on the contrast of a predetermined one cycle in the wobblingoperation, it is configured so as to switch the frequencies of the twodrive signals in the subsequent one cycle to a predetermined one cycleso as to make the focal position of the third lens unit L3 for AF tofollow the subject. The vibration-wave motor 310 can thereby cause thethird lens unit L3 for AF to move by following the movement of thesubject, and can decrease the operating noise upon causing thevibration-wave motor 310 to drive by way of the wobbling operation.

Fifth Embodiment

Next, a fifth embodiment of the present invention will be explained. Thefifth embodiment has similarly configurations for the lens barrel anddrive apparatus 340A as the aforementioned embodiment; therefore,explanations thereof will be omitted. In addition, operations of thedrive apparatus 340A during moving image photography are also similar tothe fourth embodiment. The point by which the fifth embodiment differsfrom the fourth embodiment is mainly the configuration of avibration-wave motor 350.

The configuration of a lens barrel 320A according to the fifthembodiment will be explained next. FIG. 31 is a view illustrating thelens barrel 320A according to the fifth embodiment of the presentinvention. FIG. 32 is a view illustrating the vibration-wave motor 350according to the fifth embodiment. FIG. 33 is a view illustrating theoperating principle of the vibration-wave motor 350 according to thefifth embodiment.

As shown in FIG. 31, the lens barrel 320A includes an outer fixedcylinder 331 that covers the outer circumferential part of the lensbarrel 320A, an inner first fixed cylinder 332A that is positioned moreto the inner circumferential side on the subject side than the outerfixed cylinder 331, an inner second fixed cylinder 332B that ispositioned on an image side more to the inner circumferential side thanthe outer fixed cylinder 331, and further includes the vibration-wavemotor 350 between the outer fixed cylinder 331 and the inner first fixedcylinder 332A.

The first lens unit L1 and second lens unit L2 are fixed from thesubject side to the inner first fixed cylinder 332A. In addition, thefourth lens unit L is fixed to the inner second fixed cylinder 332B. Thethird lens unit L3, which is the AF lens supported by the AF ring 334,is arranged between the second lens unit L2 and fourth lens unit L4.

As shown in FIG. 31, the vibration-wave motor 350 includes a vibrator351, moving element 355, pressurizing member 357, etc., and assumes aform that drives by moving the moving element 355.

The vibrator 351 is pivotally supported in the longitudinal direction ofthe vibrator 351 by a support pin 358 provided to a fixed member 354,and is configured so there is a degree of freedom in pressurizingdirection.

The pressurizing member 357 is provided between the fixed member 354 andvibrator 351, and makes the vibrator 351 pressurized contact the movingelement 355.

The fixed member 354 is attached to the inner first fixed cylinder 332A.By attaching the fixed member 354 to the inner first fixed cylinder332A, it comes to be possible to configure from the moving element 355,vibrator 351 to the pressurizing member 357 as one motor unit.

The moving element 355 consists of a light metal such as aluminum, and asliding plating for an abrasion resistance improvement is provided tothe surface of the sliding face. In addition, the moving element 355 isfixed to a linear guide 361, and the linear guide 361 is pivotallysupported to the inner first fixed cylinder 332A, whereby the movingelement 355 is able to move in a linear direction relative to the innerfirst fixed cylinder 332A.

A fork 362 connected to the AF ring 334 fits to an end part 355A of themoving element 355, and the AF ring 334 is driven straight ahead by thedriving of the moving element 355.

The AF ring 334 assumes a mobile structure along a linear rail 363provided to the inner first fixed cylinder 332A and inner second fixedcylinder 332B. A guide part 364 provided to the AF ring 334 fits to thelinear rail 363, and accompanying the straight ahead driving of themoving element 355, is driven in the straight ahead direction on theoptical axis direction, and is configured so as to be able to stop atthe desired position.

The vibrator 351 is configured from the piezoelectric body 353, theelastic body 352 made of metal, and a projecting part 352A for outputextraction, as shown in FIG. 32 and FIG. 33. The design of the elasticbody 352 makes so that the resonance frequencies of a verticalfirst-order vibration and a curved fourth-order vibration match. Whenthe voltage of this frequency (drive signal) is applied to thepiezoelectric body 353 and the phases of both vibrations are shifted90°, an elliptic motion is produced from the combination of the verticalvibration and curved vibration excited at the projecting part 352A, asshown in FIG. 33. Since the projecting part 352A is under pressurizedcontact to the moving element 355, a drive force is produced fromfriction. A wear-resistance material is used on the projecting part352A, and suppresses the abrasion from friction.

The piezoelectric body 353 is generally configured from a material likelead zirconate titanate, which is called by the abbreviation PZT;however, due to environmental problems in recent years, it may also beconfigured from potassium sodium niobate, potassium niobate, sodiumniobate, barium titanate, bismuth sodium titanate, bismuth potassiumtitanate, etc., which are lead-free materials.

In the fifth embodiment, the vibration-wave motor 350 is a linear-typevibration-wave motor. However, speed control is possible by controllingthe frequency, voltage and phase difference of the two drive signals inthe vibration-wave motor 350 according to the fifth embodiment;therefore, the same effects as the aforementioned fourth embodiment canbe obtained.

In addition, as in the case of equipping the ring-type ultrasonic-wavemotor according to the fourth embodiment, the conversion efficiencyrises in the fifth embodiment due to there no longer being lossoccurring when converting from rotational motion to linear motion. Forthis reason, the efficiency as a drive system overall can be raised.

Sixth Embodiment

FIG. 34 is a view illustrating a camera 502 including a lens barrel 501equipped with a vibration actuator 600 driven by a drive apparatusaccording to a sixth embodiment of the present invention.

The lens barrel 501 of the present embodiment is detachable relative tothe main body of the camera 502; however, it is not limited thereto, andmaybe be an undetachable one.

The camera 502 of the present embodiment includes an imaging opticalsystem (lens) 503 inside of the lens barrel 501.

In addition, the inside of the main body of the camera 502 is configuredfrom an imaging element 504, an AFE (Analog Front End) circuit 505, animage processing unit 506, a voice detection unit 507, buffer memory508, a recording interface 509, a monitor 510, an operation member 511,memory 512 and a CPU 513, and is connectable with a PC 514 of anexternal device.

The imaging optical system 503 is configured from a plurality of opticallenses, and causes an subject image to focus on a light receivingsurface of the imaging element 504. FIG. 34 illustrates the optical lenssystem with reference number 503 by simplifying as a single lens.

In addition, in the optical lens unit, the optical lens for AF is drivenby the driving of the vibration actuator 600.

The exposure time (shutter speed) to the imaging element 504 is decidedaccording to the operation member 511 and the conditions of the image.

The imaging element 504 is configured by a CMOS image sensor and thelike in which light-receiving elements are aligned in two-dimensions onthe light receiving surface. The imaging element 504 generates an analogimage signal by photoelectrically converting the subject image from thebeam having passed through the imaging optical system 503. The analogimage signal is input to the AFE circuit 505.

The AFE circuit 505 performs gain adjustment (signal amplificationaccording to ISO sensitivity) on the analog image signal. Morespecifically, the imaging sensitivity is changed within a predeterminedrange according to the sensitivity setting instruction from the CPU 513.The AFE circuit 505 further converts the image signal after analogprocessing by a built-in A/D conversion circuit into digital data. Thisdigital data is input to the image processing unit 506.

The image processing unit 506 performs various image processing on thedigital image data.

The memory 512 temporarily records image data in pre-process orpost-process of the image processing according to the image processingunit 506.

The voice detection unit 507 is configured from a microphone and asignal amplifier 605, mainly detects and captures a voice from thesubject direction during moving image photography, and transmits thisdata to the CPU 513.

The recording interface 509 has a connector that is not illustrated, arecording medium 515 is connected to this connector, and performs thewriting of data to the connected recording medium 515 or reading of datafrom the recording medium.

The monitor 510 is configured by a liquid crystal panel, and displaysimages, an operation menu, etc. according to an instruction from the CPU513.

The operation member 511 indicates mode dials, the arrow keys, a selectbutton and a release button, and sends an operation signal according torespective operations to the CPU 513. The setting of still imagephotography and moving image photograph is set by way of the operationmember 511.

The CPU 513 unifyingly controls actions performed by the camera 502 byexecuting a program stored in the ROM that is not illustrated. Forexample, AF (autofocus) operation control, AE (automatic exposure)operation control, and auto white balance control, etc. are performed.

The memory 512 records a sequence of image data subjected to imageprocessing. The present invention captures images corresponding to amoving image in the camera 502 of such a configuration.

FIG. 35 is a block diagram illustrating the vibration actuator 600 and adrive apparatus 601 of the vibration-wave actuator according to thesixth embodiment. The drive apparatus 601 includes an oscillation part602, phase shifting unit 604, amplifier, detection unit 606 and controlunit 603 that controls these.

The oscillation part 602 generates a drive signal of a desired frequencyaccording to the command of the control unit 603.

The phase shifting unit 604 divides the drive signal generated by theoscillation part 602 into two drive signals of different phases desiredaccording to the command of the control unit 603.

The amplifier 605 boosts the two drive signals divided by the phaseshifting unit 604 to desired voltages, respectively. The drive signalfrom the amplifier 605 is transmitted to the vibration actuator 600, andby way of the application of this drive signal, a progressive wavegenerates at the vibrator 520 described later of the vibration actuator600, whereby the moving element 528 is driven.

The rotation detection unit 606 is configured from an optical encoder,magnetic encoder, or the like, detects the position and/or speed of adriven object driven by the driving of the moving element 528, andtransmits the detection value to the control unit 603 as an electricalsignal.

The control unit 603 controls the driving of the vibration actuator 600and the movement of the vibration-wave actuator based on the drivecommand from the CPU 513 inside the lens barrel 501 or the camera mainbody. The control unit 603 receives the detection signal from therotation detection unit 606, obtains positional information and speedinformation based on this value, and controls the frequency of theoscillation part 602 of the vibration actuator 600, phase difference,etc., so as to position at the target position.

FIG. 36 is a view illustrating the lens barrel 501 equipped with thevibration actuator 600 driven by the drive apparatus according to thesixth embodiment of the present invention, and is a view of a state inwhich a ring-shaped vibration actuator 600 is incorporated into the lensbarrel 501.

The vibrator 520 is configured from an electro-mechanical energyconversion element 521 exemplified as a piezoelectric element orelectrorestrictive element that converts electrical energy to mechanicalenergy (hereinafter referred to as piezoelectric body), and an elasticbody 522 joined with the piezoelectric body 521. A 9-peak progressivewave is generated at the vibrator 520 as one example in the presentembodiment.

The elastic body 522 consists of a metal material having a largeresonance sharpness, and the shape thereof is an annular shape A grooveis cut into the opposing face of the elastic body 522 to which thepiezoelectric body 521 is joined, and the tip end face of the projectingportions (parts without grooves) are the driving face 522 a and areunder pressurized contact with the moving element 528. The reason forcutting the grooves is to bring the neutral plane of the progressivewave as near as possible to the piezoelectric body 521 side, therebymaking the amplitude of the progressive wave at the driving face 522 aamplified.

The piezoelectric body 521 is divided into the two phases (A-phase,B-phase) along the circumferential direction, and in each phase,elements for which the poles are alternating every ½ wavelength arealigned, and a ¼ wavelength interval is open between the A-phase andB-phase.

Below the piezoelectric body 521, a non-woven fabric 523, pressure plate524 and pressurizing member 525 are arranged.

The non-woven fabric 523 is felt, for example, is arranged below thepiezoelectric body 521, and makes so that vibration of the vibrator 520does not convey to the pressure plate 524 or pressurizing member 525.

The pressure plate 524 is made so as to receive the pressure of thepressurizing member 525.

The pressurizing member 525 is arranged below the pressure plate 524,and causes an applied pressure to generate.

In the present embodiment, although the pressurizing member 525 is adisk spring, it does not need to be a disk spring, and may be a coilspring or a wave spring.

The pressurizing member 525 is retained by a pressing ring 526, and thepressing ring 526 is fixed to a fixed member 527.

The moving element 528 consists of a light metal such as aluminum, and asliding material for abrasion resistance improvement is provided on thesurface of sliding face.

In order to absorb vibrations in the longitudinal direction of themoving element 528, a vibration absorbing member 529 like rubber isarranged on the moving element 528, and thereon, an output transfermember 530 is arranged.

With the output transfer member 530, the pressurizing direction andradial direction are defined by way of a bearing 531 provided to thefixed member 527, whereby the pressurizing direction and radialdirection of the moving element 528 are defined.

The output transfer member 530 has a projecting part 532 and, therefrom,a fork connecting to a cam ring 533 fits, whereby the cam ring 336 isrotated along with the rotation of the output transfer member 530.

In the cam ring 533, a key groove 534 is cut obliquely in the cam ring533, and a fixed pin 536 provided to the AF ring 535 fits together withthe key groove 534.

Then, by the cam ring 533 rotationally driving, the AF ring 535 isdriven in the straight ahead direction on the optical axis direction,and is made so as to be able to stop at the desired position.

The fixed member 527, the pressing ring 526 is attached by a spring tothe fixed member 314, and by the fixed member 527 attaching this, it ispossible to configure from the output transfer member 530, movingelement 528, vibrator 520 until the pressurizing member 525 as one motorunit.

The phase shifting unit 604 of FIG. 35 separates the drive signalgenerated by the oscillation part 602 into drive signals of the A-phaseand B-phase having different phases from each other. These drive signalsof the A-phase and B-phase are applied at the respective electrodes ofthe piezoelectric body 521.

In the case of the phase difference existing between the drive signalsof the A-phase and B-phase, a wave generating at the driving face 522 aof the elastic body 522 by way of the vibration excited by thepiezoelectric body 521 is a progressive wave, causing the moving body528 to rotate.

FIG. 37 is a graph showing the relationship between the phase differenceof the A-phase and B-phase and the rotational speed of the movingelement 528.

As illustrated, when the phase difference of the A-phase and B-phase is+/−90°, the rotational speed of the moving element 528 becomes thefastest. Then, when the phase differences approaches 0 (or 180), thewave generating at the driving face 522 a becomes a standing wave ratherthan a progressive wave, and the rotation of the moving element 528stops.

FIG. 38 is a graph showing the relationship between the frequency of thedrive signal and the impedance of the vibration actuator 600. Theportion shown by fs in the graph is the drive frequency used upondriving the lens.

During driving of the vibration actuator 600, since it is preferable tostart the vibration actuator 600 from low speed, it is common for thefrequency of the drive signal applied to the piezoelectric body 521 tostart from a higher frequency than the drive frequency (hereinafterreferred to as startup frequency), and gradually lower to the drivefrequency.

For ease of explanation of this startup frequency, first, a comparativeembodiment relative to the present embodiment will be explained. In thecomparative embodiment, upon driving the vibration actuator 600, thephase difference of the drive signals of the A-phase and B-phase appliedto the piezoelectric body 521 is fixed at 90°, for example.

In this case, the startup frequency starts from a frequency f1 betweenthe drive frequency fs and a resonance frequency f3 of the nexthigh-order vibration mode than the vibration mode (drive mode) in whichthis drive frequency fs is included, and gradually lowers to the drivefrequency fs.

The reason for a higher frequency than the resonance frequency f3 of thenext high-order vibration mode than the vibration mode not using f1 inthis way is because control of the operation is difficult by theimpedance of the vibration actuator 600 increasing upon the frequency ofthe drive signal exceeding the resonance frequency f3.

However, in the case of this comparative embodiment, the A-phase andB-phase of the startup frequency f1 with the phase difference of 90° areapplied to the piezoelectric body 521, simultaneously with the powersource turning ON. The startup frequency f1 cannot be set to asufficiently high frequency due to being smaller than f3, and thevibrator 520 of the vibration actuator 600 suddenly starts a largevibration, and there is a possibility of an outbreak sound generating.

Therefore, in the present embodiment, the electricity application to thepiezoelectric body 521 starts from the frequency f2, exceeding theresonance frequency f3 of the next higher-order vibration mode than thedrive vibration mode.

The resonance frequency f3 must be exceeded upon lowering the frequencydown to the drive frequency fs also in the present embodiment.

Upon exceeding the resonance frequency f3, if the moving element 528drives, there is a possibility of the movement of the vibration actuator600 becoming unstable as mentioned above.

Therefore, in the present embodiment, the phase difference between theA-phase and B-phase is set to 0 or 180° until arriving at the drivefrequency. However, 0° and 180° are not strict values and, for example,it is a permissible range up to on the order of +/−5°, so long as arange in which the moving element 528 will not rotate.

Then, when the vibration frequency arrives at the drive frequency fs,the phase difference between the A-phase and B-phase is set to about90°. When the phase difference becomes 90°, the moving element 528starts rotation, and lens driving by way of the vibration actuator 600becomes possible.

According to the present embodiment, since not a progressive wave, butrather a standing wave is produced at the driving face 522 a of thevibrator 520 until the vibration frequency arrives at the drivefrequency fs, torque is not transmitted to the moving element 528.Therefore, since the vibration actuator 600 is stopped, it does notbring about a malfunction in operation. On the other hand, vibration ofthe vibrator 520 is started from a small vibration; therefore, there isa low possibility of outbreak sound.

FIG. 39 is a graph showing an example of lens driving by the vibrationactuator 600 according to the sixth embodiment.

First, at the time t1 at which voltage supply to the vibration actuator600 is started, since the phase difference is 0, the lens remainsstopped. Therefore, outbreak sound does not generate by the lenssuddenly starting driving.

Then, at t2 at which the frequency of the drive signal is made todecrease, and exceeds the resonance frequency f3 to reach the drivefrequency fs, a phase difference between the A-phase and B-phase isproduced. In the present embodiment, it is about 90°. It should be notedthat, although 90° has good efficiency, it is not limited thereto.

Then, the phase difference is set to about 0° at the time t3 at whichthe lens 503 arrives at the desired position. The lens 503 therebystops.

A phase difference between the A-phase and B-phase is produced again atthe time t4 at which the necessity for driving of the lens 503 arisesagain. On this occasion, in a case of causing the lens 503 to drive inthe reverse direction to the movement from time t2 to t3, the phasedifference is set to −90°.

The following effects are possessed according to the present embodimentabove.

(1) Conventionally, upon startup of the vibration actuator 600, thepower source voltage is slowly input, and starts up at a slightly higherfrequency than the drive frequency. However, the outbreak sound uponturning ON the power source is still present with this. During movingimage photography, etc., outbreak sound generates every time turning ONthe actuator. In addition, even with suppressing abnormal noisegeneration, the frequency upon startup only widens until before theresonance point of the next mode.

However, with the present invention, the frequency upon startup widensuntil the next drive mode, and by starting up from a state in which thevibration is sufficiently small, the generation of outbreak sound uponstartup is decreased.

(2) By setting the phase difference of drive signals upon turning thepower source ON to 0 or 180°, even if the vibrator 520 starts vibration,there will not be an event of the moving element 528 starting to move,and thus a malfunction will not occur upon the vibration frequency ofthe drive signal exceeding the resonance frequency.

The present invention is not to be limited to the embodiments explainedabove, and various modifications and changes like those shown below arepossible, and these also are within the scope of the present invention.

MODIFIED EXAMPLE 6

In the present embodiment, the lens barrel 501 is detachable relative tothe main body of the camera 502; however, it is not limited thereto, andmay be undetachable.

MODIFIED EXAMPLE 7

In addition, in the present embodiment, the vibration actuator 600 isexplained with an example as ring type equipping the lens inside;however, it is not limited thereto, and may be miniature type thatrotates about a different axis from the axis line of the retainingcylinder, outside of the lens retaining cylinder.

Seventh Embodiment

Hereinafter, a seventh embodiment of the present invention will beexplained by referencing the drawings, etc.

FIG. 40 is a schematic view illustrating the overall configuration of acamera 701 according to the seventh embodiment.

FIG. 41 is a diagram illustrating the configuration of anultrasonic-wave motor 720 according to the seventh embodiment.

FIG. 42 is a diagram illustrating the configuration of a drive apparatus730 connected to the ultrasonic-wave motor 720 according to the seventhembodiment.

It should be noted that, in FIG. 40, the front-back direction of thecamera 701 is defined as the X direction, the left-right direction isdefined as the Y direction, and the vertical direction is defined as theZ direction.

The camera 701 includes a camera housing 702 having an imaging element703, and a lens barrel 710 as shown in FIG. 40, and is a digital camerathat can not only photograph still images of a subject, but also movingimages.

The lens barrel 710 is an interchangeable lens that is detachable fromthe camera housing 702. The lens barrel 710 includes a lens 711 (opticalmember), a cam cylinder 712, a position detection unit 713, anultrasonic-wave motor 720 (vibration actuator), a drive apparatus 730(drive apparatus of vibration actuator), etc. It should be noted thatthe lens barrel 710 may be established as an integral unit with thecamera housing 702.

The lens 711 is supported by the cam cylinder 712, and is a focus lensthat performs focal adjustment by moving in the optical axis direction(X direction) by way of the drive power of the ultrasonic-wave motor720.

The cam cylinder 712 is connected with a rotational element 721(described later) of the ultrasonic-wave motor 720, convertingrotational motion of the ultrasonic-wave motor 720 into linear motion inthe optical axis direction (X direction) to make the lens 711 mobile inthe optical axis direction (X direction).

The position detection unit 713 is an encoder that detects the positionof the lens 711, which moves in the optical axis direction (Xdirection).

The ultrasonic-wave motor 720 is an annular progressive wave-typeultrasonic-wave motor of rotational type, and is configured from anannular rotational element 721, and a vibrator 722 (vibrating body) thatpressurized contacts the rotational element 721, as shown in FIG. 41.

The vibrator 722 is configured from an annular elastic body 723, and anannular piezoelectric element 724 (piezoelectric body) joined to thiselastic body 723.

The elastic body 723 is an elastic member to which comb-teeth areprovided to a face that pressurized contacts the rotational element 721.

The piezoelectric element 724 is joined to a face on the opposite sideto the contact face with the rotational element 721 of the elastic body723, and has electrode patterns A-phase and B-phase consisting of twophases. The electrode patterns A-phase and B-phase are polarized so thatthe polarity differs alternatingly for each in the circumferentialdirection.

The ultrasonic-wave motor 720 causes a progressive vibration wave togenerate at the vibrator 722 by applying the two-phase alternatingsignal having respectively different phases to the electrode patternsA-phase and B-phase of the piezoelectric element 724, and the rotationalelement 721 under pressurized contact to the vibrator 722 is excited bythis vibration wave, whereby a drive force to rotate in thecircumferential direction (clockwise direction G, counter-clockwisedirection H) is generated.

The drive apparatus 730 is a device that controls driving of theultrasonic-wave motor 720, as shown in FIG. 42. The drive apparatus 730includes a control unit 731, a drive circuit 732, a storage unit 733(frequency storage unit), a speed detection unit 734, etc.

The control unit 731 is a control circuit that unifyingly controls eachpart of the drive apparatus 730, and is configured from a CPU, etc., forexample. The control unit 731 realizes various functions according tothe present invention in cooperation with the aforementioned hardware,by reading various programs stored in the storage unit 733 and executingas appropriate.

The control unit 731 is connected to the drive circuit 732, storage unit733, speed detection unit 734, etc. The control unit 731 includes aspeed control part 731 a, a stop determination part 731 b, etc.

The speed control part 731 a controls the drive operation of theultrasonic-wave motor 720 and rotational speed n via the drive circuit732. More specifically, the speed control part 731 a causes the phasedifference p and drive frequency f of alternating signals input to therespective electrode patterns A-phase and B-phase of the piezoelectricelement 724 of the ultrasonic-wave motor 720 to change so as to controlthe drive operation and rotational speed n of the ultrasonic-wave motor720. Herein, drive operation refers to an operation of rotational motion(refer to FIG. 41) in the positive rotational direction G of therotational element 721 of the ultrasonic-wave motor 720, rotationalmotion in the reverse rotational direction H (refer to FIG. 41), orstopping.

The stop determination part 731 b determines whether or not theultrasonic-wave motor 720 has stopped, based on the state of the phasedifference p of the two-phase alternating signals applied to thepiezoelectric element 724, and information of the rotational speed n ofthe ultrasonic-wave motor 720 detected by the speed detection unit 734.More specifically, the stop determination part 731 b determines that theultrasonic-wave motor 720 stopped when confirming that the phasedifference of the alternating signals applied to the piezoelectricelement 724 is p=0, and the rotational speed detected by the speeddetection unit 734 is n=0.

The drive circuit 732 is connected to the electrodes of the respectiveelectrode patterns A-phase and B-phase of the piezoelectric element 724,and is a circuit that generates alternating signals set to apredetermined phase difference p and predetermined drive frequency f,based on the drive signal input from the speed control part 731 a.

The storage unit 733 is a storage device such as semiconductor memorydevice for storing programs, information, etc. required in the operationof the drive apparatus 730. In addition, the storage unit 733 storesinformation of the drive frequency of the alternating signals applied tothe ultrasonic-wave motor 720 while stopped as a stop frequency fx(described later).

The speed detection unit 734 inputs information of a position W of thelens 711 detected from the position detection unit 713, and detects therotational speed n of the rotational element 721 based on thisinformation of position W.

The speed detection unit 734 outputs information of the detectedrotational speed n to the control unit 731.

Next, the characteristics of the ultrasonic-wave motor 720 will beexplained.

FIG. 43 provides graphs showing the characteristics of theultrasonic-wave motor 720 according to the seventh embodiment.

FIG.43A is a graph showing the relationship between the drive frequencyf of the alternating signals applied to the ultrasonic-wave motor 720and the rotational speed n. FIG.43B is a graph showing the relationshipbetween the phase difference p of the alternating signals applied to theultrasonic-wave motor 720 and the rotational speed n.

As shown in FIG.43A, with the ultrasonic-wave motor 720, it is possibleto change the rotational speed n thereof by changing the drive frequencyf between fr and f0. More specifically, the ultrasonic-wave motor 720has a characteristic of the rotational speed n rising when lowering thedrive frequency f thereof from f0. For example, in the case of the drivefrequency f=f1, the rotational speed becomes n=N1, and in the case off=f2, then becomes n=N2 (f1>f2, N2>N1).

Herein, fr in FIG.43A is the mechanical resonance frequency of thevibrator 722 of the ultrasonic-wave motor 720. In addition, f0 is afrequency at which the rotational element 721 of the ultrasonic-wavemotor 720 in a state with no load starts to rotate from the stoppedstate. By taking into account the stability, etc. of control of theultrasonic-wave motor 720, the relationships between the drive frequencyf, fr, and f0 are generally desired to be fr<f<f0, and in the control ofthe ultrasonic-wave motor 720, uses the characteristic of decreasing tothe right from fr in FIG. 43A.

In addition, based on the inductance L of the secondary winding of atransformer (not illustrated) provided to the drive circuit 732 of thedrive apparatus 730 and the capacitance C of the piezoelectric element724 of the vibrator 722, since making f0 match the electrical resonancefrequency fc obtained from the formula below is desirable from theaspect of an electricity consumption reduction, f0=fc is established inthe seventh embodiment.

fc=1/{2π√(LC)}

As stated above, f0 is the frequency at which the rotational element 721of the ultrasonic-wave motor 720 in a state with no load starts rotationfrom the stopped state; whereas, fα in FIG.43A is the frequency at whichthe rotational element 721 in a state in which the lens 711, camcylinder 721, etc. are connected starts rotation from the stopped state.The rotational element 721 to which the lens 711, etc. are connectedcannot begin rotation at the drive frequency f=f0 due to the weight ofthe lens 711, etc., the frictional resistance of the sliding part, etc.,and begins rotation at the drive frequency f=fα.

The relationship between fα and f0 is f0>fα.

The stop frequency fx stored in the storage unit 733 is the drivefrequency of the alternating signals applied to the ultrasonic-wavemotor 720 while stopped as described above; therefore, in order todecrease the electricity consumption thereof, it is a frequencyarbitrarily set between the aforementioned f0 and fα. In the seventhembodiment, the stop frequency fx is set to a frequency in the middle off0 and fα, i.e. fx=(f0+fα)/2.

In addition, as shown in FIG.43B, with the ultrasonic-wave motor 720, itis possible to cause the drive operation to change by the phasedifference p of the alternating signals applied to the respectiveelectrode patterns A-phase and B-phase of the piezoelectric element 724being controlled. In the seventh embodiment, the ultrasonic-wave motor720 rotates in the positive rotational direction G (refer to FIG. 41)when the phase difference of the alternating signals applied to therespective electrode pattern A-phase and B-phase is set to p=+90°, androtates in the reverse rotational direction H when the phase differenceis set to p=−90° (refer to FIG. 41). In addition, it stops when thephase difference is p=0°. At this time, the lens 711 moves to thesubject side (X1 side) when the ultrasonic-wave motor 720 rotates in thepositive rotational direction G, and moves to the imaging element 703side (X2 side) when rotating in the reverse rotational direction H, asshown in FIG. 40.

Next, the driving of the ultrasonic-wave motor 720 and operation of thelens 711 moving by way of this driving will be explained with thewobbling operation as an example.

FIG. 44 is a timing chart illustrating the driving pattern of a driveapparatus 730 in the wobbling operation according to the seventhembodiment. In FIG. 44, the vertical axis shows in order from the topthe drive voltage v, drive frequency f, phase difference p androtational speed n of the ultrasonic-wave motor 720 and the position Wof the lens 711, and the horizontal axis shows time (t1 to t29).

Herein, wobbling operation is one of the focusing means for focusing ona subject automatically during moving image photography. In the wobblingoperation, the drive apparatus 730 drives the ultrasonic-wave motor 720based on a command signal inputted from a control unit of the camera 701that is not illustrated, and during moving image photography, repeats asequence of operations (t5 to t16) to cause the position of the lens 11to move from an initial position Wi to Wbe on the subject side (X1 side)and then stop, cause to move from Wbe to Waf on the imaging element 703side (X2 side) and then stop, and cause to move from Waf to W0 and thenstop, as shown in FIG. 44.

At t4, when moving image photography of the camera 701 is started, thespeed control part 731 a of the drive apparatus 730 applies alternatingsignals having a drive frequency f=f0 and phase difference p=+90° to thepiezoelectric element 724 of the ultrasonic motor 720. At this time, thelens 711 is stopped at the initial position Wi.

At t5, the speed control part 731 a causes the drive frequency of theultrasonic-wave motor 720 to change in the lowering direction from f0 tof1, in order to cause the position W of the lens 711 to move from Wi toWbe, accompanying the start of the wobbling operation.

At t6, when gradually lowering the drive frequency f from f0 to f1, uponpassing fα, the ultrasonic-wave motor 720 starts rotation in theclockwise direction G, and the rotational speed reaches n=N1. Along withthis, the position W of the lens 711 also starts movement from Wi to thesubject side (X1 side). Then, in accordance with the position W of thelens 711 arriving at Wbe, the speed control part 731 a changes the phasedifference p of the alternating signals applied to the ultrasonic-wavemotor 720 from +90° to 0° to cause the ultrasonic-wave motor 720 tostop.

At t7, the stop determination part 731 b of the control unit 731determines whether the ultrasonic-wave motor 720 has stopped, based onthe phase difference p of the alternating signals, and information ofthe rotational speed n output from the speed detection unit 734. If thestop determination part 731 b determines that the ultrasonic-wave motor720 has stopped, the speed control part 731 a reads information of astop frequency fx stored in the storage unit 733, and changes the drivefrequency f in the rising direction from f1 to fx.

At t8, the speed control part 731 a causes the ultrasonic-wave motor 720to stop while the drive frequency is f=fx.

At t9, the speed control part 731 a causes the drive frequency f of theultrasonic-wave motor 720 to change in the lowering direction from fx tof2 in order to cause the position W of the lens 711 to move from Wbe toWaf.

At t10, the speed control part 731 a gradually changes the phasedifference p of the alternating signals applied to the piezoelectricelement 724 from 0° to −90°.

The ultrasonic-wave motor 720 thereby rotates in the reverse rotationaldirection (H direction) and the position W of the lens 711 moves fromWbe to Waf.

Then, in accordance with the position W of the lens 711 arriving at Waf,the speed control part 731 a changes the phase difference p of thealternating signals applied to the piezoelectric element 724 from −90°to 0° to cause the ultrasonic-wave motor 720 to stop.

At t11, when the stop determination part 731 b determines that theultrasonic-wave motor 720 has stopped based on information of the phasedifference p of the alternating signals and of the rotational speed noutput from the speed detection unit 734, the speed control part 731 areads information of the stop frequency fx in the storage unit 311, andchanges the drive frequency f in the rising direction from f2 to fx.

At t12, the speed control part 731 a causes the ultrasonic-wave motor720 to stop while the drive frequency is f=fx.

At t13, the speed control part 731 a causes the drive frequency f of theultrasonic-wave motor 720 to change from fx to f1, in order to cause theposition W of the lens 711 to move from Waf to W0.

At t14, the speed control part 731 a gradually changes the phasedifference p of the alternating signals applied to the ultrasonic-wavemotor 720 from 0° to +90°.

The ultrasonic-wave motor 720 thereby rotates in the positive rotationaldirection (G direction), and the position W of the lens 711 moves fromWaf to W0.

Then, in accordance with the position of the lens 711 arriving at W0,the speed control part 731 a changes the phase difference p of thealternating signals applied to the piezoelectric element 724 from +90°to 0° to cause the ultrasonic-wave motor 720 to stop.

At t15, when the stop determination part 731 b determines that theultrasonic-wave motor 720 has stopped, based on information of the phasedifference p of the alternating signals and the rotational speed noutput form the speed detection unit 734, the speed control part 731 areads information of the stop frequency fx in the storage unit 733, andchanges the drive frequency f in the rising direction from f1 to fx.

At t16, the speed control part 731 a causes the ultrasonic-wave motor720 to stop while the drive frequency is f=fx.

The above sequence of the wobbling operation in t5 to t16 comes to anend, and the drive apparatus 730 repeatedly performs the same operationagain from t17.

Next, the operation pattern of the ultrasonic-wave motor in the wobblingoperation of a comparative example will be explained. It should be notedthat, in the following explanation and in the drawings, explanations foroperations similar to the aforementioned operation pattern of theultrasonic-wave motor 720 of the present invention will be omitted, andonly differing operations will be explained.

FIG. 45 is a timing chart illustrating the drive pattern of the driveapparatus in the wobbling operation of a comparative example. Similarlyto FIG. 44, in FIG. 45, the vertical axis shows in order from the topthe drive voltage v, drive frequency f, phase difference p androtational speed n of the ultrasonic-wave motor and the position W ofthe lens, and the horizontal axis shows time (t1 to t29).

As shown in FIG. 45, in the drive pattern of the drive apparatus in thewobbling operation of the comparative example, if the position W of thelens moves from Wi to Wbe, at t7, the speed control unit changes thedrive frequency f in the lowering direction from f1 to f2 in order tomove the position W of the lens in a subsequent operation from Wbe toWaf. Then, the speed control part maintains the drive frequency at f=f2,while causing the position W of the lens to move from Wbe to Waf at t10.In contrast, the drive pattern of the present invention differs from thedrive pattern of the comparative example in the point of, the speedcontrol part 731 a causes the ultrasonic-wave motor 720 to stop with thedrive frequency set at f=fx at t8, as mentioned above. In addition, thisis similar for t11 to t13 and t15 to 17.

Next, the difference in the amount of power consumption of theultrasonic-wave motors between the seventh embodiment and thecomparative example will be explained.

FIG. 46 is a graph comparing the amount of power consumption of theultrasonic-wave motors between the seventh embodiment and thecomparative example. In FIG. 46, the vertical axis shows the amount ofelectrical power consumed by the control of the ultrasonic-wave motor,and the horizontal axis shows the control time.

Since the ultrasonic-wave motor 720 has a trend of the electricityconsumption thereof decreasing as the drive frequency f approaches f0(=fc), when the ultrasonic-wave motor 720 is stopped, the driveapparatus 730 of the present invention changes the drive frequency fthereof to f=fx in the rising direction so as to approach f0.

On the other hand, as mentioned above, when the ultrasonic-wave motor isstopped, in preparation for the subsequent operation, a conventionaldrive apparatus changes the drive frequency f thereof to f1, f2 or thelike, which are in a direction distancing from f0.

Herein, due to being fx>f1>f2, the electricity consumption duringstopping of the ultrasonic-wave motor 720 is smaller for the control ofthe drive apparatus 730 of the present invention, than the control bythe drive apparatus of the comparative example.

In FIG. 46, for a case of the stop time of the ultrasonic-wave motorduring control being long (condition 1) and a case of being short(condition 2), the electricity consumption is compared according to thedrive apparatus 730 of the present invention and the drive apparatus ofthe comparative example, respectively.

As shown in FIG. 46, in either case, the electricity consumption waslower for the drive apparatus 730 of the present invention than for thedrive apparatus of the comparative example, and thus the effect of areduction in the electricity consumption by the ultrasonic-wave motor720 of the drive apparatus 730 of the present invention could beconfirmed. In addition, since the stop time also lengthens as thecontrol time lengthens, the aforementioned effect of a reduction in theelectricity consumption of the present invention becomes moreremarkable.

As explained above, there are the following such effects in the driveapparatus 730 and lens barrel 710 according the seventh embodiment.

(1) The drive apparatus 730 can reduce the electricity consumption whilestopping of the ultrasonic-wave motor 720 during control, due to makingthe drive frequency f of the alternating signals applied to thepiezoelectric element 724 change to fx in the rising direction so as toapproach the electric resonance frequency fc, in the case of theultrasonic-wave motor 720 being stopped.

(2) Since the stop determination part 731 b determines whether theultrasonic-wave motor 720 has stopped based on the state of the phasedifference p of the alternating signals applied to the piezoelectricelement 724 and the rotational speed n of the rotational element 721,the speed control part 731 a causes the drive frequency f to changeprior to the ultrasonic-wave motor 720 completely stopping, and thus canavoid the ultrasonic-wave motor 720 from malfunctioning.

(3) Since the speed detection unit 734 detects the rotational speed n ofthe rotational element 721 of the ultrasonic-wave motor 720 based on thepositional information of the lens 711, an existing position detectionunit 713 provided to the lens barrel 710 can be used without providing asensor for detecting the rotational speed n to the rotational element721, whereby a reduction in the size of the lens barrel 710 and a costreduction can be achieved.

(4) Due to using the drive apparatus 730 in driving of the lens 711 ofthe lens barrel 710, it is possible to reduce the electricityconsumption of the ultrasonic-wave motor 720 continuously driving, in afocus operation such as the wobbling operation of the lens 711.

MODIFIED EXAMPLE 8

The seventh embodiment shows an example in which the stop frequency fxstored in the storage unit 733 is set to a frequency in the middle of f0and fα, i.e. fx=(f0+fα)/2; however, it is not limited thereto.

As mentioned above, fx can be arbitrarily set so long as between f0 andfα; therefore, it is also possible to set the stop frequency to fx=fα,for example. By configuring as such, it is possible to reduce theelectricity consumption during stopping of the ultrasonic-wave motor720, and quicken the response time from a stopped state of theultrasonic-wave motor 720 to rotational motion.

In addition, due to being f0=fc if setting the stop frequency to fx=f0,the drive apparatus 730 can cause the electricity consumption duringstopping of the ultrasonic-wave motor 720 to reduce the mostefficiently.

MODIFIED EXAMPLE 9

The seventh embodiment shows an example in which the speed detectionunit 734 detects the rotational speed n of the rotational element 721based on positional information of the position detection unit 713;however, it is not limited thereto. For example, a sensor for detectingthe rotational speed n may be provided to the rotational element 721,and the rotational speed n of the rotational element 721 may be detecteddirectly.

MODIFIED EXAMPLE 10

The seventh embodiment shows an example in which the ultrasonic-wavemotor 720 is an annular progressive wave-type ultrasonic-wave motor ofrotational type; however, it is not limited thereto. For example, it isalso possible to employ a rod-shaped ultrasonic-wave motor of rotationaltype.

MODIFIED EXAMPLE 11

The seventh embodiment shows an example of using the drive circuit 732to which a transformer is provided; however, it is also possible toemploy a drive circuit to which an inductor is provided, for example.

MODIFIED EXAMPLE 12

The seventh embodiment explains an example of a wobbling operationduring moving image photography of the lens barrel 710; however, it isnot limited thereto. It is also possible to employ a differentoperation, for example, an auto-focus operation during still imagephotography, and similar effects as the present invention can beobtained thereby.

The embodiments and modified examples explained above are merelyexemplifications after all, and the present invention is not limited tothese contents so long as the characteristics of the invention are notimpaired. In addition, the embodiments and modified examples explainedabove may be realized by combinations thereof, so long as thecharacteristics of the invention are not impaired.

1. A drive apparatus comprising: a vibrating part having anelectro-mechanical energy conversion element to which two drive signalshaving variable phase difference are inputted; a relative motion partthat relatively moves in relation to the vibrating part, by way of adrive force generated at the vibrating part according to vibration ofthe electro-mechanical energy conversion element; and a control unitthat inputs the two drive signals to the electro-mechanical energyconversion element at a startup frequency that is higher than a drivefrequency used in driving, while maintaining at phase difference atwhich the relative motion part is in a stopped state, and when graduallyreducing the frequency of the two drive signals from the startupfrequency and reaching the drive frequency, sets the phase difference toa phase difference that enables the relative motion part to relativelymove in relation to the vibrating part.
 2. The drive apparatus accordingto claim 1, wherein the startup frequency is a frequency of at least aresonance frequency of a next higher-order vibration mode of a vibrationmode including the drive frequency.
 3. The drive apparatus according toclaim 1, wherein the phase difference at which the relative motion partmaintains a stopped state is +/−15° from 0° or 180°.
 4. A method ofdriving a vibration actuator, wherein the vibration actuator comprises:a vibrating part having an electro-mechanical energy conversion elementto which two drive signals having variable phase difference areinputted; and a relative motion part that relatively moves in relationto the vibrating part, by way of a drive force generated at thevibrating part according to vibration of the electro-mechanical energyconversion element, the method comprising the steps of: during startupof the vibration actuator, inputting the two drive signals to theelectro-mechanical energy conversion element in a state maintaining aphase difference therebetween at a phase difference at which therelative motion part stays in a stopped state, and at a startupfrequency that is higher than the drive frequency used in driving of thevibration actuator; and setting the phase difference to a phasedifference at which the relative motion part can relatively move inrelation to the vibrating part, upon gradually reducing the frequency ofthe two drive signals from the startup frequency and reaching the drivefrequency.
 5. An optical device comprising the drive apparatus accordingto claim
 1. 6. A drive apparatus for controlling driving of a vibrationactuator that generates a drive force, by applying two-phase alternatingsignals having different phases to a piezeoelectric body provided to avibrating body to cause the vibrating body to vibrate, the driveapparatus comprising: a speed control unit that controls a drive speedof the vibration actuator, by causing a frequency of the two-phasealternating signals applied to the piezoelectric body to change; afrequency storage unit that stores a predetermined frequency; and a stopdetermination unit that determines whether the vibration actuator isstopped, wherein the speed control unit causes the frequency of thealternating signals applied to the piezoelectric body to change to thepredetermined frequency stored in the frequency storage unit, in a caseof the stop determination unit having determined that the vibrationactuator is stopped.
 7. A drive apparatus that controls driving of avibration actuator that generates a drive force, by applying two-phasealternating signals having different phases to a piezeoelectric bodyprovided to a vibrating body, the drive apparatus comprising: a speedcontrol unit that controls a drive speed of the vibration actuator, bycausing a frequency of the two-phase alternating signals applied to thepiezoelectric body to change; and a stop determination unit thatdetermines whether the vibration actuator is stopped, wherein the speedcontrol unit causes the frequency of the alternating signals applied tothe piezoelectric body to change so as to approach an electricalresonance frequency, in a case of the stop determination unit havingdetermined that the vibration actuator is stopped.
 8. The driveapparatus according to claim 7, wherein the speed control unit causesthe frequency of the alternating signals applied to the piezoelectricbody to change to a rising direction, in a case of the stopdetermination unit having determined that the vibration actuator isstopped.
 9. The drive apparatus according to claim 7, wherein the speedcontrol unit causes the frequency of the alternating signals applied tothe piezoelectric body to change to a frequency at which the vibrationactuator begins driving from a stopped state, in a case of the stopdetermination unit having determined that the vibration actuator isstopped.
 10. The drive apparatus according to claim 7, wherein the speedcontrol unit causes the frequency of the alternating signal applied tothe piezoelectric body to change to the electrical resonance frequency,in a case of the stop determination unit having determined that thevibration actuator is stopped.
 11. The drive apparatus according toclaim 7, wherein the electrical resonance frequency is a resonancefrequency of a capacitance of the piezoelectric body and an inductanceof a drive circuit applying the alternating signal to the piezoelectricbody.
 12. The drive apparatus according to claim 6, further comprising aspeed detection unit that detects a drive speed of the vibrationactuator, wherein the speed control unit controls the drive speed of thevibration actuator by causing a phase difference of the two-phasealternating signals applied to the piezoelectric body to change, andwherein the stop determination unit determines whether the vibrationactuator stopped, based on a state of the phase difference of thetwo-phase alternating signals applied to the piezoelectric body, andinformation of the drive speed detected by way of the speed detectionunit.
 13. An optical device comprising: the drive apparatus for avibration actuator according to claim 6; a vibration actuator that isdriven by way of the drive apparatus for a vibration actuator; and anoptical member that is driven by way of the vibration actuator.
 14. Anoptical device comprising: an electro-mechanical energy conversionelement to which a drive signal is applied from a drive circuit; avibrating body that generates a drive force by way of theelectro-mechanical energy conversion element; a moving body that isdriven by the drive force of the vibrating body; and a control unit thatperforms first control to control so that the drive signal becomes afirst frequency when causing the moving body to drive, and performssecond control to control so that the drive signal becomes a secondfrequency when the moving body is stopped, wherein the drive circuit hasa smaller amount of power consumption when the drive signal is thesecond drive signal than when the drive signal is the first drivesignal.